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Archive for April 20th, 2008

man ln

Apr-20-2008 By WTF *Nix

NAME

ln – make links between files

SYNOPSIS

ln [OPTION]… [-T] TARGET LINK_NAME   (1st form)
ln [OPTION]… TARGET              (2nd form)
ln [OPTION]… TARGET… DIRECTORY     (3rd form)
ln [OPTION]… -t DIRECTORY TARGET…  (4th form)

DESCRIPTION

In  the    1st form, create a link to TARGET with the name LINK_NAME.  In
the 2nd form, create a link to TARGET in the current directory.    In the
3rd  and  4th  forms, create links to each TARGET in DIRECTORY.    Create
hard links by default, symbolic links with –symbolic.    When  creating
hard links, each TARGET must exist.

Mandatory  arguments  to  long  options are mandatory for short options
too.

–backup[=CONTROL]
make a backup of each existing destination file

-b     like –backup but does not accept an argument

-d, -F, –directory
allow the superuser to attempt to hard link  directories    (note:
will  probably  fail  due  to  system restrictions, even for the
superuser)

-f, –force
remove existing destination files

-n, –no-dereference
treat destination that is a symlink to a directory as if it were
a normal file

-i, –interactive
prompt whether to remove destinations

-s, –symbolic
make symbolic links instead of hard links

-S, –suffix=SUFFIX
override the usual backup suffix

-t, –target-directory=DIRECTORY
specify the DIRECTORY in which to create the links

-T, –no-target-directory
treat LINK_NAME as a normal file

-v, –verbose
print name of each file before linking

–help display this help and exit

–version
output version information and exit

The   backup   suffix   is  `~’,  unless  set  with  –suffix  or  SIM-
PLE_BACKUP_SUFFIX.  The version control method may be selected via  the
–backup  option  or  through the VERSION_CONTROL environment variable.
Here are the values:

none, off
never make backups (even if –backup is given)

numbered, t
make numbered backups

existing, nil
numbered if numbered backups exist, simple otherwise

simple, never
always make simple backups

AUTHOR

Written by Mike Parker and David MacKenzie.

REPORTING BUGS

Report bugs to <bug-coreutils@gnu.org>.

COPYRIGHT

Copyright (C) 2005 Free Software Foundation, Inc.
This is free software.  You may redistribute copies  of    it  under  the
terms       of        the      GNU      General       Public      License
<http://www.gnu.org/licenses/gpl.html>.    There is NO WARRANTY,  to  the
extent permitted by law.

SEE ALSO

The  full  documentation  for ln is maintained as a Texinfo manual.  If
the info and ln programs are properly installed at your site, the  com-
mand

info ln

should give you access to the complete manual.

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man find

Apr-20-2008 By WTF *Nix

NAME

find – search for files in a directory hierarchy

SYNOPSIS

find [-H] [-L] [-P] [path...] [expression]

DESCRIPTION

This  manual page documents the GNU version of find.  GNU find searches
the directory tree rooted at each given file  name  by  evaluating  the
given  expression  from left to right, according to the rules of prece-
dence (see section OPERATORS), until the outcome  is  known  (the  left
hand  side  is  false  for and operations, true for or), at which point
find moves on to the next file name.

If you are using find in an environment    where  security  is  important
(for example if you are using it to seach directories that are writable
by other users), you should read the “Security Considerations”  chapter
of the findutils documentation, which is called Finding Files and comes
with findutils.     That document also includes a    lot  more  detail  and
discussion  than  this  manual  page,  so you may find it a more useful
source of information.

OPTIONS

The `-H’, `-L’ and `-P’    options  control  the  treatment  of  symbolic
links.  Command-line arguments following these are taken to be names of
files or directories to be examined, up    to  the  first    argument  that
begins  with `-’, `(‘, `)’, `,’, or `!’.  That argument and any follow-
ing arguments are taken to be the expression describing what is    to  be
searched  for.    If  no paths are given, the current directory is used.
If no expression is given, the expression `-print’  is  used  (but  you
should probably consider using `-print0′ instead, anyway).

This  manual  page  talks  about  `options’ within the expression list.
These options control the behaviour of find but are  specified  immedi-
ately  after  the  last path name.  The three `real’ options `-H’, `-L’
and `-P’ must appear before the first path name, if at all.

-P     Never follow symbolic links.  This  is  the  default  behaviour.
When find examines or prints information a file, and the file is
a symbolic link, the information used shall be  taken  from  the
properties of the symbolic link itself.

-L     Follow symbolic links.  When find examines or prints information
about files, the information used shall be taken from the  prop-
erties  of  the file to which the link points, not from the link
itself (unless it is a broken symbolic link or find is unable to
examine  the file to which the link points).  Use of this option
implies -noleaf.    If you later use the -P option,  -noleaf  will
still  be  in  effect.   If -L is in effect and find discovers a
symbolic link to a subdirectory during its search, the subdirec-
tory pointed to by the symbolic link will be searched.

When the -L option is in effect, the -type predicate will always
match against the type of the file that a symbolic  link    points
to rather than the link itself (unless the symbolic link is bro-
ken).  Using -L causes the -lname and -ilname predicates    always
to return false.

-H     Do  not  follow symbolic links, except while processing the com-
mand line arguments.  When find examines or  prints  information
about  files, the information used shall be taken from the prop-
erties of the symbolic link itself.   The only exception to this
behaviour is when a file specified on the command line is a sym-
bolic link, and the link can be resolved.  For  that  situation,
the  information    used is taken from whatever the link points to
(that is, the link is followed).    The information about the link
itself  is used as a fallback if the file pointed to by the sym-
bolic link cannot be examined.  If -H is in effect  and  one  of
the  paths specified on the command line is a symbolic link to a
directory, the contents  of  that  directory  will  be  examined
(though of course -maxdepth 0 would prevent this).

If more than one of -H, -L and -P is specified, each overrides the oth-
ers; the last one appearing on the command line takes effect.  Since it
is  the    default,  the  -P  option should be considered to be in effect
unless either -H or -L is specified.

GNU find frequently stats files during the processing  of  the  command
line itself, before any searching has begun.  These options also affect
how those arguments are processed.  Specifically, there are a number of
tests  that  compare files listed on the command line against a file we
are currently considering.  In each case, the  file  specified  on  the
command    line  will  have been examined and some of its properties will
have been saved.  If the named file is in fact a symbolic link, and the
-P  option  is  in effect (or if neither -H nor -L were specified), the
information used for the comparison will be taken from  the  properties
of  the symbolic link.  Otherwise, it will be taken from the properties
of the file the link points to.    If find cannot follow  the  link  (for
example    because it has insufficient privileges or the link points to a
nonexistent file) the properties of the link itself will be used.

When the -H or -L options are in effect, any symbolic links  listed  as
the  argument of -newer will be dereferenced, and the timestamp will be
taken from the file to which the symbolic link points.  The  same  con-
sideration applies to -anewer and -cnewer.

The  -follow  option has a similar effect to -L, though it takes effect
at the point where it appears (that is, if -L is not used  but  -follow
is, any symbolic links appearing after -follow on the command line will
be dereferenced, and those before it will not).

EXPRESSIONS

The expression is made up of options (which  affect  overall  operation
rather than the processing of a specific file, and always return true),
tests (which return a true or false value),  and  actions  (which  have
side effects and return a true or false value), all separated by opera-
tors.  -and is assumed where the operator is omitted.

If the expression contains no actions other than -prune, -print is per-
formed on all files for which the expression is true.

OPTIONS
All options always return true.    Except for -follow and -daystart, they
always take effect, rather than being processed only when  their  place
in  the    expression  is reached.  Therefore, for clarity, it is best to
place them at the beginning of the expression.  A warning is issued  if
you don’t do this.

-daystart
Measure  times  (for  -amin,  -atime,  -cmin, -ctime, -mmin, and
-mtime) from the beginning of today rather than  from  24  hours
ago.   This  option only affects tests which appear later on the
command line.

-depth Process each directory’s contents before the directory itself.

-d     A synonym for -depth, for compatibility  with  FreeBSD,  NetBSD,
MacOS X and OpenBSD.

-follow
Deprecated;  use    the  -L  option instead.  Dereference symbolic
links.  Implies -noleaf.    The -follow option affects only  those
tests  which appear after it on the command line.  Unless the -H
or -L option has been specified, the  position  of  the  -follow
option  changes the behaviour of the -newer predicate; any files
listed as the argument of -newer will be    dereferenced  if  they
are  symbolic  links.  The same consideration applies to -anewer
and -cnewer.  Similarly, the -type predicate will  always  match
against  the  type  of  the  file that a symbolic link points to
rather than the link itself.  Using -follow  causes  the    -lname
and -ilname predicates always to return false.

-help, –help
Print a summary of the command-line usage of find and exit.

-ignore_readdir_race
Normally,  find will emit an error message when it fails to stat
a file.  If you give this option and a file is  deleted  between
the  time find reads the name of the file from the directory and
the time it tries to stat the file, no  error  message  will  be
issued.     This also applies to files or directories whose names
are given on the command line.  This option takes effect at  the
time  the  command  line    is  read,  which means that you cannot
search one part of the filesystem with this option on  and  part
of  it  with  this  option off (if you need to do that, you will
need to issue two find commands instead, one with the option and
one without it).

-maxdepth levels
Descend at most levels (a non-negative integer) levels of direc-
tories below the command line arguments.     `-maxdepth  0′  means
only  apply the tests and actions to the command line arguments.

-mindepth levels
Do not apply any tests or actions at levels less than levels  (a
non-negative  integer).    `-mindepth  1′ means process all files
except the command line arguments.

-mount Don’t descend directories on other  filesystems.     An  alternate
name  for  -xdev,  for compatibility with some other versions of
find.

-noignore_readdir_race
Turns off the effect of -ignore_readdir_race.

-noleaf
Do not optimize by assuming that    directories  contain  2  fewer
subdirectories  than  their  hard  link  count.    This option is
needed when searching filesystems that do not  follow  the  Unix
directory-link  convention, such as CD-ROM or MS-DOS filesystems
or AFS volume mount points.  Each directory  on  a  normal  Unix
filesystem  has  at  least  2  hard  links: its name and its `.’
entry.  Additionally, its subdirectories (if any)  each  have  a
`..’   entry linked to that directory.  When find is examining a
directory, after it has statted 2 fewer subdirectories than  the
directory’s link count, it knows that the rest of the entries in
the directory are non-directories (`leaf’ files in the directory
tree).   If  only the files’ names need to be examined, there is
no need to stat them;  this  gives  a  significant  increase  in
search speed.

-regextype type
Changes  the  regular expression syntax understood by -regex and
-iregex tests which occur later on the command line.  Currently-
implemented  types  are  emacs (this is the default), posix-awk,
posix-basic, posix-egrep and posix-extended.

-version, –version
Print the find version number and exit.

-warn, -nowarn
Turn warning messages on or off.    These warnings apply  only  to
the  command  line  usage, not to any conditions that find might
encounter when it searches directories.  The  default  behaviour
corresponds  to -warn if standard input is a tty, and to -nowarn
otherwise.

-xdev  Don’t descend directories on other filesystems.

TESTS
Numeric arguments can be specified as

+n     for greater than n,

-n     for less than n,

n      for exactly n.

-amin n
File was last accessed n minutes ago.

-anewer file
File was last accessed more recently than file was modified.  If
file is a symbolic link and the -H option or the -L option is in
effect, the access time of the file it points to is always used.

-atime n
File  was  last  accessed n*24 hours ago.  When find figures out
how many 24-hour periods ago the file  was  last    accessed,  any
fractional part is ignored, so to match -atime +1, a file has to
have been accessed at least two days ago.

-cmin n
File’s status was last changed n minutes ago.

-cnewer file
File’s status was last changed more recently than file was modi-
fied.   If  file    is a symbolic link and the -H option or the -L
option is in effect, the    status-change  time  of  the  file  it
points to is always used.

-ctime n
File’s status was last changed n*24 hours ago.  See the comments
for -atime to understand how rounding affects the interpretation
of file status change times.

-empty File is empty and is either a regular file or a directory.

-false Always false.

-fstype type
File  is    on  a  filesystem  of type type.  The valid filesystem
types vary among different versions of Unix; an incomplete  list
of filesystem types that are accepted on some version of Unix or
another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K.   You  can
use  -printf  with  the  %F  directive  to see the types of your
filesystems.

-gid n File’s numeric group ID is n.

-group gname
File belongs to group gname (numeric group ID allowed).

-ilname pattern
Like -lname, but the match  is  case  insensitive.   If  the  -L
option  or  the  -follow    option is in effect, this test returns
false unless the symbolic link is broken.

-iname pattern
Like -name, but the match is case insensitive.  For example, the
patterns    `fo*’  and  `F??’  match  the file names `Foo’, `FOO’,
`foo’, `fOo’, etc.   In these patterns, unlike  filename    expan-
sion  by    the shell, an initial ‘.’ can be matched by ‘*’.  That
is, find -name *bar will match the file `.foobar’.   Please note
that  you should quote patterns as a matter of course, otherwise
the shell will expand any wildcard characters in them.

-inum n
File has inode number n.    It  is    normally  easier  to  use  the
-samefile test instead.

-ipath pattern
Behaves  in  the same way as -iwholename.  This option is depre-
cated, so please do not use it.

-iregex pattern
Like -regex, but the match is case insensitive.

-iwholename pattern
Like -wholename, but the match is case insensitive.

-links n
File has n links.

-lname pattern
File is a symbolic link whose contents match shell pattern  pat-
tern.  The metacharacters do not treat `/’ or `.’ specially.  If
the -L option or the -follow option  is  in  effect,  this  test
returns false unless the symbolic link is broken.

-mmin n
File’s data was last modified n minutes ago.

-mtime n
File’s  data was last modified n*24 hours ago.  See the comments
for -atime to understand how rounding affects the interpretation
of file modification times.

-name pattern
Base  of    file  name  (the  path    with  the  leading directories
removed) matches    shell  pattern    pattern.   The    metacharacters
(`*’,  `?’,  and `[]‘) match a `.’ at the start of the base name
(this is a change in findutils-4.2.2; see section STANDARDS CON-
FORMANCE    below).  To ignore a directory and the files under it,
use -prune; see an example in  the  description  of  -wholename.
Braces  are  not    recognised  as being special, despite the fact
that some shells including Bash  imbue  braces  with  a  special
meaning  in  shell patterns.  The filename matching is performed
with the use of the fnmatch(3) library function.     Don’t    forget
to  enclose  the    pattern  in quotes in order to protect it from
expansion by the shell.

-newer file
File was modified more recently than file.  If file  is  a  sym-
bolic  link and the -H option or the -L option is in effect, the
modification time of the file it points to is always used.

-nouser
No user corresponds to file’s numeric user ID.

-nogroup
No group corresponds to file’s numeric group ID.

-path pattern
See -wholename.    The predicate -path is also supported by HP-UX
find.

-perm mode
File’s  permission  bits    are  exactly mode (octal or symbolic).
Since an exact match is required, if you want to use  this  form
for  symbolic  modes,  you  may have to specify a rather complex
mode string.  For example ‘-perm    g=w’  will  only  match  files
which  have  mode 0020 (that is, ones for which group write per-
mission is the only permission set).  It is more likely that you
will want to use the ‘/’ or ‘-’ forms, for example ‘-perm -g=w’,
which matches any file with group  write    permission.   See  the
EXAMPLES section for some illustrative examples.

-perm -mode
All  of the permission bits mode are set for the file.  Symbolic
modes are accepted in this form, and this is usually the way  in
which  would want to use them.  You must specify ‘u’, ‘g’ or ‘o’
if you use a symbolic mode.   See the EXAMPLES section for  some
illustrative examples.

-perm /mode
Any  of the permission bits mode are set for the file.  Symbolic
modes are accepted in this form.    You must specify ‘u’,  ‘g’  or
‘o’  if  you  use a symbolic mode.  See the EXAMPLES section for
some illustrative examples.  If no permission bits in  mode  are
set,  this  test    currently  matches no files.  However, it will
soon be changed to match any file (the idea is to be  more  con-
sistent with the behaviour of perm -000).

-perm +mode
Deprecated,  old way of searching for files with any of the per-
mission bits in mode set.  You should use -perm  /mode  instead.
Trying to use the ‘+’ syntax with symbolic modes will yield sur-
prising results.    For example, ‘+u+x’ is a valid    symbolic  mode
(equivalent to +u,+x, i.e. 0111) and will therefore not be eval-
uated as -perm +mode but instead as  the    exact  mode  specifier
-perm  mode  and so it matches files with exact permissions 0111
instead of files with any execute bit set.  If  you  found  this
paragraph  confusing,  you’re  not alone – just use -perm /mode.
This form of the -perm test  is  deprecated  because  the  POSIX
specification  requires  the  interpretation of a leading ‘+’ as
being part of a symbolic mode, and so we switched to  using  ‘/’
instead.

-regex pattern
File  name  matches regular expression pattern.  This is a match
on the whole path, not a search.    For example, to match  a  file
named `./fubar3′, you can use the regular expression `.*bar.’ or
`.*b.*3′, but not `f.*r3′.  The regular  expressions  understood
by  find    are by default Emacs Regular Expressions, but this can
be changed with the -regextype option.

-samefile name
File refers to the same inode as name.   When -L is  in  effect,
this can include symbolic links.

-size n[cwbkMG]
File uses n units of space.  The following suffixes can be used:

`b’    for 512-byte blocks (this is the default if no suffix  is
used)

`c’    for bytes

`w’    for two-byte words

`k’    for Kilobytes (units of 1024 bytes)

`M’    for Megabytes (units of 1048576 bytes)

`G’    for Gigabytes (units of 1073741824 bytes)

The  size  does  not  count  indirect  blocks, but it does count
blocks in sparse files that are not actually allocated.  Bear in
mind  that the `%k’ and `%b’ format specifiers of -printf handle
sparse  files  differently.   The  `b’  suffix  always   denotes
512-byte    blocks and never 1 Kilobyte blocks, which is different
to the behaviour of -ls.

-true  Always true.

-type c
File is of type c:

b      block (buffered) special

c      character (unbuffered) special

d      directory

p      named pipe (FIFO)

f      regular file

l      symbolic link; this is never true if the -L option or the
-follow  option is in effect, unless the symbolic link is
broken.  If you want to search for symbolic links when -L
is in effect, use -xtype.

s      socket

D      door (Solaris)

-uid n File’s numeric user ID is n.

-used n
File was last accessed n days after its status was last changed.

-user uname
File is owned by user uname (numeric user ID allowed).

-wholename pattern
File name matches shell pattern pattern.    The metacharacters  do
not treat `/’ or `.’ specially; so, for example,
find . -wholename ‘./sr*sc’
will  print an entry for a directory called ‘./src/misc’ (if one
exists).    To ignore a whole directory tree,  use    -prune    rather
than  checking every file in the tree.  For example, to skip the
directory `src/emacs’ and all files and  directories  under  it,
and  print the names of the other files found, do something like
this:
find . -wholename ‘./src/emacs’ -prune -o -print

-xtype c
The same as -type unless the file is a symbolic link.  For  sym-
bolic  links:  if the -H or -P option was specified, true if the
file is a link to a file of type c; if the -L  option  has  been
given,  true  if    c is `l’.  In other words, for symbolic links,
-xtype checks the type of the file that -type does not check.

ACTIONS
-delete
Delete files; true if removal succeeded.    If the removal failed,
an  error  message  is issued.  Use of this action automatically
turns on the ‘-depth’ option.

-exec command ;
Execute command; true if 0 status is  returned.    All  following
arguments to find are taken to be arguments to the command until
an argument consisting of `;’ is encountered.  The  string  `{}’
is  replaced by the current file name being processed everywhere
it occurs in the arguments to the command, not just in arguments
where  it  is alone, as in some versions of find.  Both of these
constructions might need to be escaped (with a `\’) or quoted to
protect them from expansion by the shell.  See the EXAMPLES sec-
tion for examples of the use of the `-exec’ option.  The    speci-
fied  command is run once for each matched file.    The command is
executed in the  starting  directory.    There  are  unavoidable
security    problems  surrounding  use  of    the  -exec option; you
should use the -execdir option instead.

-exec command {} +
This variant of the -exec option runs the specified  command  on
the  selected  files, but the command line is built by appending
each selected file name at the end; the total number of  invoca-
tions  of  the  command  will  be  much  less than the number of
matched files.  The command line is built in much the  same  way
that  xargs builds its command lines.  Only one instance of ‘{}’
is allowed within the command.  The command is executed  in  the
starting directory.

-execdir command ;

-execdir command {} +
Like  -exec, but the specified command is run from the subdirec-
tory containing the matched file,  which    is  not  normally  the
directory  in  which  you started find.  This a much more secure
method for invoking commands, as it avoids race conditions  dur-
ing  resolution  of the paths to the matched files.  As with the
-exec option, the ‘+’ form of -execdir will build a command line
to  process more than one matched file, but any given invocation
of command will only list files that exist in the same subdirec-
tory.   If  you use this option, you must ensure that your $PATH
environment variable does not reference the  current  directory;
otherwise, an attacker can run any commands they like by leaving
an appropriately-named file in a directory in which you will run
-execdir.

-fls file
True;  like -ls but write to file like -fprint.  The output file
is always created, even if the predicate is never matched.   See
the  UNUSUAL FILENAMES section for information about how unusual
characters in filenames are handled.

-fprint file
True; print the full file name into file file.  If file does not
exist  when  find is run, it is created; if it does exist, it is
truncated.  The file names “/dev/stdout”  and  “/dev/stderr”
are  handled  specially;    they  refer to the standard output and
standard error output, respectively.  The output file is    always
created,    even  if  the  predicate  is  never  matched.  See the
UNUSUAL FILENAMES section  for  information  about  how  unusual
characters in filenames are handled.

-fprint0 file
True;  like  -print0 but write to file like -fprint.  The output
file is always created, even if the predicate is never  matched.
See  the    UNUSUAL  FILENAMES  section  for information about how
unusual characters in filenames are handled.

-fprintf file format
True; like -printf but write to file like -fprint.   The    output
file  is always created, even if the predicate is never matched.
See the UNUSUAL FILENAMES  section  for  information  about  how
unusual characters in filenames are handled.

-ok command ;
Like  -exec  but    ask the user first (on the standard input); if
the response does not start with `y’ or `Y’, do not run the com-
mand,  and  return  false.   If the command is run, its standard
input is redirected from /dev/null.

-print True; print the full file name on the standard output,  followed
by  a  newline.     If  you  are  piping  the output of find into
another program and there is the faintest possibility  that  the
files  which you are searching for might contain a newline, then
you should seriously consider using the `-print0′ option instead
of  `-print’.  See the UNUSUAL FILENAMES section for information
about how unusual characters in filenames are handled.

-okdir command ;
Like -execdir but ask the user first (on the standard input); if
the response does not start with `y’ or `Y’, do not run the com-
mand, and return false.  If the command  is  run,  its  standard
input is redirected from /dev/null.

-print0
True;  print the full file name on the standard output, followed
by a null character  (instead  of  the  newline  character  that
`-print’ uses).  This allows file names that contain newlines or
other types of white space to be correctly interpreted  by  pro-
grams  that process the find output.  This option corresponds to
the `-0′ option of xargs.

-printf format
True; print format on  the  standard  output,  interpreting  `\’
escapes  and `%’ directives.  Field widths and precisions can be
specified as with the `printf’ C    function.   Please  note  that
many  of    the  fields are printed as %s rather than %d, and this
may mean that flags don’t work as you might expect.   This  also
means  that the `-’ flag does work (it forces fields to be left-
aligned).  Unlike -print, -printf does not add a newline at  the
end of the string.  The escapes and directives are:

\a     Alarm bell.

\b     Backspace.

\c     Stop  printing from this format immediately and flush the
output.

\f     Form feed.

\n     Newline.

\r     Carriage return.

\t     Horizontal tab.

\v     Vertical tab.

\      ASCII NUL.

\\     A literal backslash (`\’).

\NNN   The character whose ASCII code is NNN (octal).

A `\’ character followed by any other character is treated as an
ordinary character, so they both are printed.

%%     A literal percent sign.

%a     File’s  last  access time in the format returned by the C
`ctime’ function.

%Ak    File’s last access time in the  format  specified    by  k,
which  is    either `@’ or a directive for the C `strftime’
function.    The possible values for k  are    listed    below;
some  of  them might not be available on all systems, due
to differences in `strftime’ between systems.

@      seconds since Jan. 1, 1970, 00:00 GMT.

Time fields:

H      hour (00..23)

I      hour (01..12)

k      hour ( 0..23)

l      hour ( 1..12)

M      minute (00..59)

p      locale’s AM or PM

r      time, 12-hour (hh:mm:ss [AP]M)

S      second (00..61)

T      time, 24-hour (hh:mm:ss)

+      Date and time,  separated    by  ‘+’,  for  example
`2004-04-28+22:22:05′.   The time is given in the
current timezone (which may be affected  by  set-
ting the TZ environment variable).  This is a GNU
extension.

X      locale’s time representation (H:M:S)

Z      time zone (e.g., EDT), or nothing if no time zone
is determinable

Date fields:

a      locale’s abbreviated weekday name (Sun..Sat)

A      locale’s full weekday name, variable length (Sun-
day..Saturday)

b      locale’s abbreviated month name (Jan..Dec)

B      locale’s full month name, variable  length  (Jan-
uary..December)

c      locale’s  date  and time (Sat Nov 04 12:02:33 EST
1989)

d      day of month (01..31)

D      date (mm/dd/yy)

h      same as b

j      day of year (001..366)

m      month (01..12)

U      week number of year with Sunday as first  day  of
week (00..53)

w      day of week (0..6)

W      week  number  of year with Monday as first day of
week (00..53)

x      locale’s date representation (mm/dd/yy)

y      last two digits of year (00..99)

Y      year (1970…)

%b     The amount of disk space used for this file  in  512-byte
blocks. Since disk space is allocated in multiples of the
filesystem  block    size  this  is    usually  greater  than
%s/1024,  but  it    can  also  be smaller if the file is a
sparse file.

%c     File’s last status change time in the format returned  by
the C `ctime’ function.

%Ck    File’s last status change time in the format specified by
k, which is the same as for %A.

%d     File’s depth in the directory tree; 0 means the file is a
command line argument.

%D     The  device  number  on which the file exists (the st_dev
field of struct stat), in decimal.

%f     File’s name with any leading  directories    removed  (only
the last element).

%F     Type  of the filesystem the file is on; this value can be
used for -fstype.

%g     File’s group name, or numeric group ID if the  group  has
no name.

%G     File’s numeric group ID.

%h     Leading directories of file’s name (all but the last ele-
ment).  If the file name contains no slashes (since it is
in  the  current  directory)  the %h specifier expands to
“.”.

%H     Command line argument under which file was found.

%i     File’s inode number (in decimal).

%k     The amount of disk space used for this file in 1K blocks.
Since  disk  space  is  allocated    in  multiples  of  the
filesystem  block    size  this  is    usually  greater  than
%s/1024,  but  it    can  also  be smaller if the file is a
sparse file.

%l     Object of symbolic link (empty string if file  is    not  a
symbolic link).

%m     File’s  permission bits (in octal).  This option uses the
‘traditional’ numbers  which  most  Unix  implementations
use,  but    if  your  particular  implementation  uses  an
unusual ordering of octal permissions bits, you will  see
a    difference between the actual value of the file’s mode
and the output of %m.   Normally you will want to have  a
leading  zero  on this number, and to do this, you should
use the # flag (as in, for example, ‘%#m’).

%M     File’s permissions (in symbolic form, as for  ls).   This
directive is supported in findutils 4.2.5 and later.

%n     Number of hard links to file.

%p     File’s name.

%P     File’s  name  with  the name of the command line argument
under which it was found removed.

%s     File’s size in bytes.

%t     File’s last modification time in the format  returned  by
the C `ctime’ function.

%Tk    File’s  last modification time in the format specified by
k, which is the same as for %A.

%u     File’s user name, or numeric user ID if the user  has  no
name.

%U     File’s numeric user ID.

%y     File’s  type  (like  in ls -l), U=unknown type (shouldn’t
happen)

%Y     File’s type (like    %y),  plus  follow  symlinks:  L=loop,
N=nonexistent

A  `%’  character  followed  by any other character is discarded
(but the other character is printed).

The %m and %d directives support the # , 0 and + flags, but  the
other  directives  do  not, even if they print numbers.  Numeric
directives that do not support these flags include G, U, b, D, k
and  n.  The `-’ format flag is supported and changes the align-
ment of a field from right-justified (which is the  default)  to
left-justified.

See  the    UNUSUAL  FILENAMES  section  for information about how
unusual characters in filenames are handled.

-prune If -depth is not given, true; if the file is a directory, do not
descend into it.
If -depth is given, false; no effect.

-quit  Exit  immediately.  No child processes will be left running, but
no more paths specified on the command line will    be  processed.
For example, find /tmp/foo /tmp/bar -print -quit will print only
/tmp/foo.  Any command lines  which  have  been  built  up  with
-execdir    … {} + will be invoked before find exits.   The exit
status may or may not be zero, depending on whether an error has
already occurred.

-ls    True; list current file in `ls -dils’ format on standard output.
The block counts are of 1K blocks, unless the environment  vari-
able  POSIXLY_CORRECT  is set, in which case 512-byte blocks are
used.  See the UNUSUAL FILENAMES section for  information  about
how unusual characters in filenames are handled.

UNUSUAL FILENAMES
Many  of  the  actions  of find result in the printing of data which is
under the control of other users.  This    includes  file    names,    sizes,
modification  times  and  so forth.  File names are a potential problem
since they can contain any character  except  ‘\0′  and    ‘/’.   Unusual
characters in file names can do unexpected and often undesirable things
to your terminal (for example, changing the settings of    your  function
keys on some terminals).  Unusual characters are handled differently by
various actions, as described below.

-print0, -fprint0
Always print the exact filename, unchanged, even if  the    output
is going to a terminal.

-ls, -fls
Unusual  characters are always escaped.  White space, backslash,
and double quote characters are printed using  C-style  escaping
(for  example ‘\f’, ‘\”‘).  Other unusual characters are printed
using an octal escape.  Other printable characters (for -ls  and
-fls  these  are    the characters between octal 041 and 0176) are
printed as-is.

-printf, -fprintf
If the output is not going to a terminal, it is  printed    as-is.
Otherwise, the result depends on which directive is in use.  The
directives %D, %F, %g, %G, %H, %Y, and %y expand to values which
are  not    under control of files’ owners, and so are printed as-
is.  The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s,  %t,
%u and %U have values which are under the control of files’ own-
ers but which cannot be used to send arbitrary data to the  ter-
minal,  and  so these are printed as-is.    The directives %f, %h,
%l, %p and %P are quoted.  This quoting is performed in the same
way  as  for  GNU ls.  This is not the same quoting mechanism as
the one used for    -ls and -fls.    If you are able to decide what
format  to use for the output of find then it is normally better
to use ‘\0′ as a terminator than to use newline, as  file  names
can contain white space and newline characters.

-print, -fprint
Quoting  is handled in the same way as for -printf and -fprintf.
If you are using find in a script or in a  situation  where  the
matched  files  might  have arbitrary names, you should consider
using -print0 instead of -print.

The -ok and -okdir actions print the current filename as-is.  This  may
change in a future release.

OPERATORS
Listed in order of decreasing precedence:

( expr )
Force precedence.

! expr True if expr is false.

-not expr
Same as ! expr, but not POSIX compliant.

expr1 expr2
Two  expressions in a row are taken to be joined with an implied
“and”; expr2 is not evaluated if expr1 is false.

expr1 -a expr2
Same as expr1 expr2.

expr1 -and expr2
Same as expr1 expr2, but not POSIX compliant.

expr1 -o expr2
Or; expr2 is not evaluated if expr1 is true.

expr1 -or expr2
Same as expr1 -o expr2, but not POSIX compliant.

expr1 , expr2
List; both expr1 and expr2 are always evaluated.    The  value  of
expr1  is  discarded;  the  value  of  the  list is the value of
expr2.      The comma operator can be useful for    searching  for
several  different types of thing, but traversing the filesystem
hierarchy only once.   The -fprintf action can be used  to  list
the various matched items into several different output files.

STANDARDS CONFORMANCE

The  following  options    are  specified in the POSIX standard (IEEE Std
1003.1, 2003 Edition):

-H     This option is supported.

-L     This option is supported.

-name  This option is supported, but POSIX conformance depends  on  the
POSIX  conformance  of the system’s fnmatch(3) library function.
As of findutils-4.2.2, shell metacharacters (‘*’.  ‘?’  or  ‘[]‘
for  example) will match a leading ‘.’, because IEEE PASC inter-
pretation 126 requires this.   This is a    change    from  previous
versions of findutils.

-type  Supported.    POSIX  specifies  `b’, `c’, `d’, `l’, `p’, `f’ and
`s’.  GNU find also supports `D’, representing a Door, where the
OS provides these.

-ok    Supported.   Interpretation of the response is not locale-depen-
dent (see ENVIRONMENT VARIABLES).

-newer Supported.  If the file specified is  a  symbolic  link,    it  is
always  dereferenced.  This is a change from previous behaviour,
which used to take the relevant time from the symbolic link; see
the HISTORY section below.

Other predicates
The predicates `-atime’, `-ctime’, `-depth’, `-group’, `-links’,
`-mtime’, `-nogroup’, `-nouser’,    `-perm’,  `-print’,  `-prune’,
`-size’, `-user’ and `-xdev’, are all supported.

The POSIX standard specifies parentheses `(‘, `)’, negation `!’ and the
`and’ and `or’ operators (`-a’, `-o’).

All other options, predicates, expressions and so forth are  extensions
beyond  the POSIX standard.  Many of these extensions are not unique to
GNU find, however.

The POSIX standard requires that

The find utility shall detect infinite loops; that is,  entering
a  previously  visited directory that is an ancestor of the last
file encountered. When it detects an infinite loop,  find  shall
write  a    diagnostic  message to standard error and shall either
recover its position in the hierarchy or terminate.

The link count of directories which  contain  entries  which  are  hard
links to an ancestor will often be lower than they otherwise should be.
This can mean that GNU find will sometimes optimise away  the  visiting
of  a subdirectory which is actually a link to an ancestor.  Since find
does not actually enter such a subdirectory, it    is  allowed  to  avoid
emitting a diagnostic message.  Although this behaviour may be somewhat
confusing, it  is  unlikely  that  anybody  actually  depends  on  this
behaviour.   If the leaf optimisation has been turned off with -noleaf,
the directory entry will always be examined and the diagnostic  message
will  be issued where it is appropriate.  Symbolic links cannot be used
to create filesystem cycles as such, but if the -L option or the  -fol-
low  option is in use, a diagnostic message is issued when find encoun-
ters a loop of symbolic links.  As with loops  containing  hard    links,
the  leaf  optimisation will often mean that find knows that it doesn’t
need to call stat() or chdir() on the symbolic link, so this diagnostic
is frequently not necessary.

The  -d option is supported for compatibility with various BSD systems,
but you should use the POSIX-compliant option -depth instead.

The POSIXLY_CORRECT environment variable does not affect the  behaviour
of  the -regex or -iregex tests because those tests aren’t specified in
the POSIX standard.

ENVIRONMENT VARIABLES

LANG   Provides a default value for the internationalization  variables
that are unset or null.

LC_ALL If  set  to a non-empty string value, override the values of all
the other internationalization variables.

LC_COLLATE
The POSIX standard specifies that this variable affects the pat-
tern matching to be used for the `-name’ option.     GNU find uses
the fnmatch(3) library function, and so support for `LC_COLLATE’
depends on the system library.

POSIX  also specifies that the `LC_COLLATE’ environment variable
affects the interpretation of the user’s response to  the  query
issued by `-ok’, but this is not the case for GNU find.

LC_CTYPE
This  variable  affects  the treatment of character classes used
with the `-name’ test, if the system’s fnmatch(3) library  func-
tion  supports  this.   It has no effect on the behaviour of the
`-ok’ expression.

LC_MESSAGES
Determines the locale to be used for internationalised messages.

NLSPATH
Determines the location of the internationalisation message cat-
alogues.

PATH   Affects the directories which are searched to find the  executa-
bles invoked by `-exec’, `-execdir’, `-ok’ and `-okdir’.

POSIXLY_CORRECT
Determines  the  block  size  used  by  `-ls’  and  `-fls’.   If
`POSIXLY_CORRECT’ is set, blocks are units of 512 bytes.    Other-
wise they are units of 1024 bytes.

TZ     Affects  the  time zone used for some of the time-related format
directives of -printf and -fprintf.

EXAMPLES

find /tmp -name core -type f -print | xargs /bin/rm -f

Find files named core in or below the directory /tmp and  delete  them.
Note  that  this  will work incorrectly if there are any filenames con-
taining newlines, single or double quotes, or spaces.

find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f

Find files named core in or below the directory /tmp and  delete  them,
processing  filenames  in  such a way that file or directory names con-
taining single or double quotes, spaces or newlines are correctly  han-
dled.   The  -name  test  comes before the -type test in order to avoid
having to call stat(2) on every file.

find . -type f -exec file ‘{}’ \;

Runs `file’ on every file in or below the  current  directory.    Notice
that the braces are enclosed in single quote marks to protect them from
interpretation as shell script punctuation.   The  semicolon  is  simi-
larly  protected  by the use of a backslash, though ‘;’ could have been
used in that case also.

find /     \( -perm -4000 -fprintf /root/suid.txt ‘%#m %u %p\n’ \) , \
\( -size +100M -fprintf /root/big.txt ‘%-10s %p\n’ \)

Traverse the filesystem just once, listing setuid files and directories
into /root/suid.txt and large files into /root/big.txt.

find $HOME -mtime 0

Search for files in your home directory which have been modified in the
last twenty-four hours.    This command works this way because  the  time
since  each  file  was  last  modified  is  divided by 24 hours and any
remainder is discarded.    That means that to match -mtime 0, a file will
have  to  have  a  modification in the past which is less than 24 hours
ago.

find . -perm 664

Search for files which have read and write permission for their    owner,
and  group,  but  which    other  users can read but not write to.  Files
which meet these criteria but have  other  permissions  bits  set  (for
example if someone can execute the file) will not be matched.

find . -perm -664

Search  for  files which have read and write permission for their owner
and group, and which other users can read, without regard to the  pres-
ence  of  any  extra  permission bits (for example the executable bit).
This will match a file which has mode 0777, for example.

find . -perm /222

Search for files which are writable by somebody (their owner, or  their
group, or anybody else).

find . -perm /220
find . -perm /u+w,g+w
find . -perm /u=w,g=w

All  three  of these commands do the same thing, but the first one uses
the octal representation of the file mode, and the other  two  use  the
symbolic  form.    These commands all search for files which are writable
by either their owner or their group.   The  files  don’t  have    to  be
writable by both the owner and group to be matched; either will do.

find . -perm -220
find . -perm -g+w,u+w

Both  these  commands  do  the  same  thing; search for files which are
writable by both their owner and their group.

find . -perm -444 -perm /222 ! -perm /111
find . -perm -a+r -perm /a+w ! -perm /a+x

These two commands both search for files that are readable  for    every-
body  (-perm -444 or -perm -a+r), have at least on write bit set (-perm
/222 or -perm /a+w) but are not executable for anybody (!   -perm  /111
and ! -perm /a+x respectively)

EXIT STATUS

find  exits  with  status  0  if  all files are processed successfully,
greater than 0 if errors occur.     This is  deliberately    a  very  broad
description,  but  if the return value is non-zero, you should not rely
on the correctness of the results of find.

SEE ALSO

locate(1), locatedb(5), updatedb(1),  xargs(1),    chmod(1),  fnmatch(3),
regex(7),  stat(2),  lstat(2), ls(1), printf(3), strftime(3), ctime(3),
Finding Files (on-line in Info, or printed).

HISTORY

As of findutils-4.2.2, shell metacharacters (‘*’. ‘?’ or ‘[]‘ for exam-
ple)  used  in filename patterns will match a leading ‘.’, because IEEE
POSIX interpretation 126 requires this.

NON-BUGS
$ find . -name *.c -print
find: paths must precede expression
Usage: find [-H] [-L] [-P] [path...] [expression]

This happens because *.c has been expanded by the  shell  resulting  in
find actually receiving a command line like this:

find . -name bigram.c code.c frcode.c locate.c -print

That  command  is of course not going to work.  Instead of doing things
this way, you should enclose the pattern in quotes:
$ find . -name ‘*.c’ -print

BUGS

The test -perm /000 currently matches no files, but for greater consis-
tency  with  -perm  -000, this will be changed to match all files; this
change will probably be made in early 2006.  Meanwhile, a warning  mes-
sage is given if you do this.

There  are  security  problems inherent in the behaviour that the POSIX
standard specifies for find, which  therefore  cannot  be  fixed.   For
example,  the  -exec action is inherently insecure, and -execdir should
be used instead.  Please see Finding Files for more information.

The best way to report a bug  is  to  use  the  form  at  http://savan-
nah.gnu.org/bugs/?group=findutils.   The  reason  for  this is that you
will then be able to track progress in fixing the problem.   Other com-
ments  about  find(1) and about the findutils package in general can be
sent to the bug-findutils mailing list.    To join the list,  send  email
to bug-findutils-request@gnu.org.

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man locate

Apr-20-2008 By WTF *Nix

NAME

locate – list files in databases that match a pattern

SYNOPSIS

locate  [-d  path | --database=path] [-e | -E | --[non-]existing] [-i |
--ignore-case] [-0 | --null] [-c | --count] [-w |  --wholename]    |-b  |
–basename]  [-l N | --limit=N] [-S | --statistics] [-r | --regex ] [-P
| -H | --nofollow] [-L | --follow]  [--version]    [-A  |    --all]    [-p  |
--print] [--help] pattern…

DESCRIPTION

This  manual  page documents the GNU version of locate.    For each given
pattern, locate searches one or more databases of file names  and  dis-
plays  the  file  names that contain the pattern.  Patterns can contain
shell-style metacharacters: `*’, `?’, and `[]‘.    The metacharacters  do
not  treat  `/’    or `.’    specially.  Therefore, a pattern `foo*bar’ can
match a file name that contains `foo3/bar’, and a pattern `*duck*’  can
match  a  file name that contains `lake/.ducky’.  Patterns that contain
metacharacters should be quoted to protect them from expansion  by  the
shell.

If  a  pattern  is  a  plain string — it contains no metacharacters –
locate displays all file names in the database that contain that string
anywhere.   If  a pattern does contain metacharacters, locate only dis-
plays file names that match the pattern exactly.  As a result, patterns
that  contain  metacharacters should usually begin with a `*’, and will
most often end with one as well.  The exceptions are patterns that  are
intended to explicitly match the beginning or end of a file name.

The  file name databases contain lists of files that were on the system
when the databases were last updated.   The  system  administrator  can
choose  the file name of the default database, the frequency with which
the databases are updated, and the directories for which  they  contain
entries; see updatedb(1).

If  locate’s  output  is going to a terminal, unusual characters in the
output are escaped in the same way as for the -print action of the find
command.   If  the  output  is  not going to a terminal, file names are
printed exactly as-is.

OPTIONS

-A, –all
Print only names which match all non-option arguments, not those
matching one or more non-option arguments.

-c, –count
Instead  of printing the matched filenames, just print the total
number of matches we found, unless –print (-p) is also present.

-d path, –database=path
Instead  of searching the default file name database, search the
file name databases in path, which is a colon-separated list  of
database    file names.  You can also use the environment variable
LOCATE_PATH to set the list of database files  to  search.   The
option  overrides  the  environment  variable  if both are used.
Empty elements in the path are taken to be synonyms for the file
name  of    the  default  database.  A database can be supplied on
stdin, using `-’ as an element of path. If more than one element
of  path is `-’, later instances are ignored (and a warning mes-
sage is printed).

The file name database format changed starting with GNU find and
locate  version 4.0 to allow machines with different byte order-
ings to share the databases.  This version of locate  can  auto-
matically  recognize  and read databases produced for older ver-
sions of GNU locate or Unix versions of locate or find.  Support
for  the    old  locate  database format will be discontinued in a
future release.

-e, –existing
Only print out such names that currently exist (instead of  such
names  that  existed  when the database was created).  Note that
this may slow down the program a lot, if there are many  matches
in the database.    If you are using this option within a program,
please note that it is possible for the file to be deleted after
locate has checked that it exists, but before you use it.

-E, –non-existing
Only  print  out such names that currently do not exist (instead
of such names that existed when the database was created).  Note
that  this  may  slow  down the program a lot, if there are many
matches in the database.

-L, –follow
If testing for the  existence  of  files    (with  the  -e    or  -E
options),  consider  broken  symbolic  links to be non-existing.
This is the default.

-P, -H, –nofollow
If testing for the  existence  of  files    (with  the  -e    or  -E
options),  treat    broken symbolic links as if they were existing
files.  The -H form of this option is provided purely for  simi-
larity with find; the use of -P is recommended over -H.

-i, –ignore-case
Ignore case distinctions in both the pattern and the file names.

-l N, –limit=N
Limit the number of matches to N.  If a limit is    set  via  this
option,  the  number  of    results printed for the -c option will
never be larger than this number.

-m, –mmap
Accepted but does nothing, for compatibility with BSD locate.

-0, –null
Use ASCII NUL as a separator, instead of newline.

-p, –print
Print search results when they normally would  not,  because  of
the presence of –statistics (-S) or –count (-c).

-w, –wholename
Match  against  the  whole  name    of  the  file as listed in the
database.  This is the default.

-b, –basename
Results are considered to match if the pattern specified matches
the  final  component  of  the  name  of a file as listed in the
database.  This final component is usually referred  to  as  the
`base name’.

-r, –regex
The  pattern specified on the command line is understood to be a
regular expression, as opposed to a glob pattern.   The  Regular
expressions  work  in  the same was as in emacs and find, except
for the fact that “.” will match    a  newline.   Filenames  whose
full  paths  match  the specified regular expression are printed
(or, in the case of the -c option, counted).   If  you  wish  to
anchor  your  regular  expression  at  the ends of the full path
name, then as is usual with regular expressions, you should  use
the characters ^ and $ to signify this.

-s, –stdio
Accepted but does nothing, for compatibility with BSD locate.

-S, –statistics
Print  various  statistics  about  each locate database and then
exit without performing a search,  unless  non-option  arguments
are given.  For compatibility with BSD, -S is accepted as a syn-
onym for –statistics.  However, the ouptut of locate -S is dif-
ferent for the GNU and BSD implementations of locate.

–help Print a summary of the options to locate and exit.

–version
Print the version number of locate and exit.

ENVIRONMENT

LOCATE_PATH
Colon-separated list of databases to search.  If the value has a
leading or trailing colon, or has two colons in a row,  you  may
get results that vary between different versions of locate.

SEE ALSO

find(1),  locatedb(5),  updatedb(1),  xargs(1),    glob(3), Finding Files
(on-line in Info, or printed)

BUGS

The locate database correctly handles  filenames  containing  newlines,
but  only if the system’s sort command has a working -z option.    If you
suspect that locate may need to return filenames  containing  newlines,
consider using its –null option.

The  best  way  to  report  a  bug  is to use the form at http://savan-
nah.gnu.org/bugs/?group=findutils.  The reason for  this  is  that  you
will then be able to track progress in fixing the problem.   Other com-
ments about locate(1) and about the findutils package in general can be
sent  to  the bug-findutils mailing list.  To join the list, send email
to bug-findutils-request@gnu.org.

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man grep

Apr-20-2008 By WTF *Nix

NAME

grep, egrep, fgrep, rgrep – print lines matching a pattern

SYNOPSIS

grep [options] PATTERN [FILE...]
grep [options] [-e PATTERN | -f FILE] [FILE...]

DESCRIPTION

grep  searches the named input FILEs (or standard input if no files are
named, or the file name – is given) for lines containing a match to the
given PATTERN.  By default, grep prints the matching lines.

In  addition,  three variant programs egrep, fgrep and rgrep are avail-
able.  egrep is the same as grep -E.  fgrep is  the  same  as  grep -F.
rgrep is the same as grep -r.

OPTIONS

-A NUM, –after-context=NUM
Print  NUM  lines  of  trailing  context    after  matching lines.
Places  a  line  containing  –  between    contiguous  groups  of
matches.

-a, –text
Process  a binary file as if it were text; this is equivalent to
the –binary-files=text option.

-B NUM, –before-context=NUM
Print NUM  lines    of  leading  context  before  matching    lines.
Places  a  line  containing  –  between    contiguous  groups  of
matches.

-b, –byte-offset
Print the byte offset within the input file before each line  of
output.

–binary-files=TYPE
If the first few bytes of a file indicate that the file contains
binary data, assume that the file is of type TYPE.  By  default,
TYPE is binary, and grep normally outputs either a one-line mes-
sage saying that a binary file matches, or no message  if  there
is  no  match.   If  TYPE  is without-match, grep assumes that a
binary file does not match; this is equivalent to the -I option.
If  TYPE    is  text,  grep  processes a binary file as if it were
text; this is  equivalent  to  the  -a  option.    Warning:  grep
–binary-files=text  might output binary garbage, which can have
nasty side effects if the output is a terminal and if the termi-
nal driver interprets some of it as commands.

-C NUM, –context=NUM
Print  NUM lines of output context.  Places a line containing –
between contiguous groups of matches.

-c, –count
Suppress normal output; instead print a count of matching  lines
for  each  input    file.  With the -v, –invert-match option (see
below), count non-matching lines.

–colour[=WHEN], –color[=WHEN]
Surround the matching string with the marker find in  GREP_COLOR
environment variable. WHEN may be `never’, `always’, or `auto’

-D ACTION, –devices=ACTION
If an input file is a device, FIFO or socket, use ACTION to pro-
cess it.    By default, ACTION is read, which means  that  devices
are  read  just  as  if  they were ordinary files.  If ACTION is
skip, devices are silently skipped.

-d ACTION, –directories=ACTION
If an input file is a directory, use ACTION to process  it.   By
default,    ACTION    is read, which means that directories are read
just as if they were ordinary files.  If ACTION is skip,    direc-
tories  are  silently skipped.  If ACTION is recurse, grep reads
all files under each directory, recursively; this is  equivalent
to the -r option.

-E, –extended-regexp
Interpret PATTERN as an extended regular expression (see below).

-e PATTERN, –regexp=PATTERN
Use PATTERN as the pattern; useful to protect patterns beginning
with -.

-F, –fixed-strings
Interpret  PATTERN as a list of fixed strings, separated by new-
lines, any of which is to be matched.

-f FILE, –file=FILE
Obtain patterns from FILE, one per line.    The  empty  file  con-
tains zero patterns, and therefore matches nothing.

-G, –basic-regexp
Interpret  PATTERN  as  a  basic regular expression (see below).
This is the default.

-H, –with-filename
Print the filename for each match.

-h, –no-filename
Suppress the prefixing of  filenames  on    output    when  multiple
files are searched.

–help Output a brief help message.

-I     Process  a  binary  file as if it did not contain matching data;
this is equivalent to the –binary-files=without-match option.

-i, –ignore-case
Ignore case distinctions in  both  the  PATTERN  and  the  input
files.

-L, –files-without-match
Suppress    normal    output;  instead  print the name of each input
file from which no output would normally have been printed.  The
scanning will stop on the first match.

-l, –files-with-matches
Suppress    normal    output;  instead  print the name of each input
file from which output would normally have  been    printed.   The
scanning will stop on the first match.

–label=LABEL
Displays input actually coming from standard input as input com-
ing from file LABEL.  This is especially useful for  tools  like
zgrep, e.g.  gzip -cd foo.gz |grep –label=foo something

–line-buffered
Use line buffering, it can be a performance penalty.

-m NUM, –max-count=NUM
Stop  reading  a file after NUM matching lines.  If the input is
standard input from a regular file, and NUM matching  lines  are
output,  grep  ensures  that the standard input is positioned to
just after the last matching line before exiting, regardless  of
the  presence of trailing context lines.    This enables a calling
process to resume a search.  When grep stops after NUM  matching
lines,  it  outputs  any trailing context lines.    When the -c or
–count option is also  used,  grep  does  not  output  a  count
greater  than NUM.  When the -v or –invert-match option is also
used, grep stops after outputting NUM non-matching lines.

–mmap If possible, use the mmap(2) system call to read input,  instead
of  the default read(2) system call.  In some situations, –mmap
yields better performance.  However, –mmap can cause  undefined
behavior    (including  core dumps) if an input file shrinks while
grep is operating, or if an I/O error occurs.

-n, –line-number
Prefix each line of output with the line number within its input
file.

-o, –only-matching
Show only the part of a matching line that matches PATTERN.

-P, –perl-regexp
Interpret PATTERN as a Perl regular expression.

-q, –quiet, –silent
Quiet;  do  not write anything to standard output.  Exit immedi-
ately with zero status if any match is found, even if  an  error
was detected.  Also see the -s or –no-messages option.

-R, -r, –recursive
Read all files under each directory, recursively; this is equiv-
alent to the -d recurse option.

–include=PATTERN
Recurse in directories only searching file matching PATTERN.

–exclude=PATTERN
Recurse in directories skip file matching PATTERN.

-s, –no-messages
Suppress error messages about nonexistent or  unreadable    files.
Portability note: unlike GNU grep, traditional grep did not con-
form to POSIX.2, because traditional grep lacked a -q option and
its  -s option behaved like GNU grep’s -q option.  Shell scripts
intended to be portable to traditional grep should avoid both -q
and -s and should redirect output to /dev/null instead.

-U, –binary
Treat  the  file(s) as binary.  By default, under MS-DOS and MS-
Windows, grep guesses the file type by looking at  the  contents
of  the first 32KB read from the file.  If grep decides the file
is a text file, it strips the CR characters  from  the  original
file  contents  (to  make  regular expressions with ^ and $ work
correctly).  Specifying -U overrules this guesswork, causing all
files  to be read and passed to the matching mechanism verbatim;
if the file is a text file with CR/LF pairs at the end  of  each
line,  this  will  cause some regular expressions to fail.  This
option has no effect on platforms other than MS-DOS and  MS-Win-
dows.

-u, –unix-byte-offsets
Report  Unix-style  byte    offsets.   This  switch causes grep to
report byte offsets as if the file were  Unix-style  text  file,
i.e. with CR characters stripped off.  This will produce results
identical to running grep on a Unix machine.  This option has no
effect  unless -b option is also used; it has no effect on plat-
forms other than MS-DOS and MS-Windows.

-V, –version
Print the version number of grep to standard error.   This  ver-
sion number should be included in all bug reports (see below).

-v, –invert-match
Invert the sense of matching, to select non-matching lines.

-w, –word-regexp
Select  only  those  lines  containing  matches  that form whole
words.  The test is that the matching substring must  either  be
at  the  beginning  of  the line, or preceded by a non-word con-
stituent character.  Similarly, it must be either at the end  of
the line or followed by a non-word constituent character.  Word-
constituent characters are letters, digits, and the  underscore.

-x, –line-regexp
Select only those matches that exactly match the whole line.

-y     Obsolete synonym for -i.

-Z, –null
Output  a  zero  byte  (the  ASCII NUL character) instead of the
character that normally follows a file name.  For example,  grep
-lZ  outputs  a  zero  byte  after each file name instead of the
usual newline.  This option makes the output  unambiguous,  even
in the presence of file names containing unusual characters like
newlines.  This option can  be  used  with  commands  like  find
-print0,    perl  -0,  sort  -z, and xargs -0 to process arbitrary
file names, even those that contain newline characters.

-z, –null-data
Treat the input as a set of lines, each  terminated  by  a  zero
byte  (the  ASCII NUL character) instead of a newline.  Like the
-Z or –null option, this option can be used with commands  like
sort -z to process arbitrary file names.

REGULAR EXPRESSIONS

A  regular  expression  is  a  pattern that describes a set of strings.
Regular expressions are constructed analogously to  arithmetic  expres-
sions, by using various operators to combine smaller expressions.

grep understands three different versions of regular expression syntax:
“basic,” “extended,” and “perl.”  In GNU grep, there is    no  difference
in  available functionality using either of the first two syntaxes.  In
other implementations, basic regular  expressions  are  less  powerful.
The following description applies to extended regular expressions; dif-
ferences for basic regular expressions are summarized afterwards.  Perl
regular    expressions  add additional functionality, but the implementa-
tion used here is undocumented and is not compatible  with  other  grep
implementations.

The  fundamental building blocks are the regular expressions that match
a single character.  Most characters, including all letters and digits,
are  regular expressions that match themselves.    Any metacharacter with
special meaning may be quoted by preceding it with a backslash.

A bracket expression is a list of characters enclosed by [ and  ].   It
matches    any  single  character in that list; if the first character of
the list is the caret ^ then it matches any character not in the  list.
For  example,  the  regular  expression [0123456789] matches any single
digit.

Within a bracket expression, a range expression consists of two charac-
ters separated by a hyphen.  It matches any single character that sorts
between the two characters, inclusive,  using  the  locale’s  collating
sequence  and  character  set.    For  example, in the default C locale,
[a-d] is equivalent to [abcd].  Many locales sort characters in dictio-
nary  order,  and in these locales [a-d] is typically not equivalent to
[abcd]; it might be equivalent to [aBbCcDd], for  example.   To    obtain
the  traditional interpretation of bracket expressions, you can use the
C locale by setting the LC_ALL environment variable to the value C.

Finally, certain named classes  of  characters  are  predefined    within
bracket expressions, as follows.  Their names are self explanatory, and
they  are  [:alnum:],  [:alpha:],  [:cntrl:],   [:digit:],   [:graph:],
[:lower:],  [:print:], [:punct:], [:space:], [:upper:], and [:xdigit:].
For example, [[:alnum:]] means  [0-9A-Za-z],  except  the  latter  form
depends upon the C locale and the ASCII character encoding, whereas the
former is independent of locale and  character  set.   (Note  that  the
brackets  in these class names are part of the symbolic names, and must
be included in addition to the brackets delimiting the  bracket    list.)
Most  metacharacters  lose  their  special  meaning  inside  lists.  To
include a literal ] place it first in the list.    Similarly, to  include
a literal ^ place it anywhere but first.  Finally, to include a literal
- place it last.

The period .  matches any single character.  The symbol \w is a synonym
for [[:alnum:]] and \W is a synonym for [^[:alnum]].

The  caret ^ and the dollar sign $ are metacharacters that respectively
match the empty string at the beginning and end of a line.  The symbols
\<  and \> respectively match the empty string at the beginning and end
of a word.  The symbol \b matches the empty string at  the  edge  of  a
word,  and \B matches the empty string provided it’s not at the edge of
a word.

A regular expression may be followed by one of several repetition oper-
ators:
?      The preceding item is optional and matched at most once.
*      The preceding item will be matched zero or more times.
+      The preceding item will be matched one or more times.
{n}    The preceding item is matched exactly n times.
{n,}   The preceding item is matched n or more times.
{n,m}  The  preceding  item  is    matched at least n times, but not more
than m times.

Two regular expressions may  be    concatenated;  the  resulting  regular
expression  matches  any  string formed by concatenating two substrings
that respectively match the concatenated subexpressions.

Two regular expressions may be joined by  the  infix  operator  |;  the
resulting  regular expression matches any string matching either subex-
pression.

Repetition takes precedence over concatenation,    which  in  turn  takes
precedence  over alternation.  A whole subexpression may be enclosed in
parentheses to override these precedence rules.

The backreference \n, where n is a single digit, matches the  substring
previously  matched by the nth parenthesized subexpression of the regu-
lar expression.

In basic regular expressions the metacharacters ?, +, {, |,  (,    and  )
lose  their  special  meaning; instead use the backslashed versions \?,
\+, \{, \|, \(, and \).

Traditional egrep did not support the { metacharacter, and  some  egrep
implementations    support \{ instead, so portable scripts should avoid {
in egrep patterns and should use [{] to match a literal {.

GNU egrep attempts to support traditional usage by assuming that  {  is
not  special if it would be the start of an invalid interval specifica-
tion.  For example, the shell command egrep ‘{1′ searches for the  two-
character  string {1 instead of reporting a syntax error in the regular
expression.  POSIX.2 allows this behavior as an extension, but portable
scripts should avoid it.

ENVIRONMENT VARIABLES

grep’s behavior is affected by the following environment variables.

A  locale  LC_foo is specified by examining the three environment vari-
ables LC_ALL, LC_foo, LANG, in that order.  The first  of  these  vari-
ables  that is set specifies the locale.  For example, if LC_ALL is not
set, but LC_MESSAGES is set to pt_BR, then Brazilian Portuguese is used
for  the  LC_MESSAGES  locale.    The  C locale is used if none of these
environment variables  are  set,  or  if  the  locale  catalog  is  not
installed,  or  if grep was not compiled with national language support
(NLS).

GREP_OPTIONS
This variable specifies default options to be placed in front of
any   explicit   options.    For    example,  if  GREP_OPTIONS  is
‘–binary-files=without-match –directories=skip’, grep  behaves
as  if the two options –binary-files=without-match and –direc-
tories=skip had been  specified  before  any  explicit  options.
Option  specifications are separated by whitespace.  A backslash
escapes the next character, so it can  be  used  to  specify  an
option containing whitespace or a backslash.

GREP_COLOR
Specifies the marker for highlighting.

LC_ALL, LC_COLLATE, LANG
These  variables specify the LC_COLLATE locale, which determines
the collating sequence used to interpret range expressions  like
[a-z].

LC_ALL, LC_CTYPE, LANG
These  variables    specify  the LC_CTYPE locale, which determines
the type of characters, e.g., which characters are whitespace.

LC_ALL, LC_MESSAGES, LANG
These variables specify the LC_MESSAGES locale, which determines
the  language that grep uses for messages.  The default C locale
uses American English messages.

POSIXLY_CORRECT
If set,  grep  behaves  as  POSIX.2  requires;  otherwise,  grep
behaves  more  like  other  GNU programs.  POSIX.2 requires that
options that follow file names must be treated as file names; by
default,    such  options are permuted to the front of the operand
list and are treated as options.    Also,  POSIX.2    requires  that
unrecognized  options  be diagnosed as “illegal”, but since they
are not really against the law the default is to    diagnose  them
as   “invalid”.    POSIXLY_CORRECT  also  disables  _N_GNU_nonop-
tion_argv_flags_, described below.

_N_GNU_nonoption_argv_flags_
(Here N is grep’s numeric process ID.)  If the ith character  of
this  environment variable’s value is 1, do not consider the ith
operand of grep to be an option, even if it appears to  be  one.
A  shell    can put this variable in the environment for each com-
mand it runs, specifying which operands are the results of  file
name  wildcard  expansion and therefore should not be treated as
options.    This  behavior    is  available  only  with  the    GNU  C
library, and only when POSIXLY_CORRECT is not set.

DIAGNOSTICS

Normally, exit status is 0 if selected lines are found and 1 otherwise.
But the exit status is 2 if an error occurred, unless the -q or –quiet
or –silent option is used and a selected line is found.

BUGS

Email  bug  reports  to    bug-gnu-utils@gnu.org.    Be sure to include the
word “grep” somewhere in the “Subject:” field.

Large repetition counts in the {n,m} construct may cause  grep  to  use
lots of memory.    In addition, certain other obscure regular expressions
require exponential time and space, and may cause grep to  run  out  of
memory.

Backreferences are very slow, and may require exponential time.

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man chroot

Apr-20-2008 By WTF *Nix

NAME

chroot – run command or interactive shell with special root directory

SYNOPSIS

chroot NEWROOT [COMMAND...]
chroot OPTION

DESCRIPTION

Run COMMAND with root directory set to NEWROOT.

–help display this help and exit

–version
output version information and exit

If no command is given, run “${SHELL} -i” (default: /bin/sh).

AUTHOR

Written by Roland McGrath.

REPORTING BUGS

Report bugs to <bug-coreutils@gnu.org>.

COPYRIGHT

Copyright (C) 2005 Free Software Foundation, Inc.
This  is  free  software.   You may redistribute copies of it under the
terms      of      the       GNU        General      Public       License
<http://www.gnu.org/licenses/gpl.html>.     There    is NO WARRANTY, to the
extent permitted by law.

SEE ALSO

The full documentation for chroot is maintained as  a  Texinfo  manual.
If  the    info  and chroot programs are properly installed at your site,
the command

info chroot

should give you access to the complete manual.

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