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How To Use Find and Locate to Search for Files on a
Linux VPS
Introduction
One problem users run into when
first dealing with a Linux machine is how to find the files they are looking
for.
This guide will cover how to use the
aptly named find
command. This will help you search for files on your VPS using a variety of
filters and parameters. We will also briefly cover the locate command, which can be used to search for commands in a
different way.
Finding
by Name
The most obvious way of searching
for files is by name.
To find a file by name, type:
find
-name "query"
This will be case sensitive, meaning
a search for "file" is different than a search for "File".
To find a file by name, but ignore
the case of the query, type:
find
-iname "query"
If you want to find all files that
don't adhere to a specific pattern, you can invert the search with
"-not" or "!". If you use "!", you must escape
the character so that bash does not try to interpret it before find can act:
find
-not -name "query_to_avoid"
Or
find
\! -name "query_to_avoid"
Finding
by Type
You can specify the type of files
you want to find with the "-type" parameter. It works like this:
find
-type type_descriptor query
Some of the most common descriptors
that you can use to specify the type of file are here:
- f: regular file
- d: directory
- l: symbolic link
- c: character devices
- b: block devices
For instance, if we wanted to find all
of the character devices on our system, we could issue this command:
find
/ -type c
/dev/parport0
/dev/snd/seq
/dev/snd/timer
/dev/autofs
/dev/cpu/microcode
/dev/vcsa7
/dev/vcs7
/dev/vcsa6
/dev/vcs6
/dev/vcsa5
/dev/vcs5
/dev/vcsa4
.
. .
We can search for all files that end
in ".conf" like this:
find
/ -type f -name "*.conf"
/var/lib/ucf/cache/:etc:rsyslog.d:50-default.conf
/usr/share/base-files/nsswitch.conf
/usr/share/initramfs-tools/event-driven/upstart-jobs/mountall.conf
/usr/share/rsyslog/50-default.conf
/usr/share/adduser/adduser.conf
/usr/share/davfs2/davfs2.conf
/usr/share/debconf/debconf.conf
/usr/share/doc/apt-utils/examples/apt-ftparchive.conf
.
. .
Filtering
by Time and Size
Find gives you a variety of ways to
filter results by size and time.
Size
You can filter by size with the use
of the "-size" parameter.
We add a suffix on the end of our
value that specifies how we are counting. These are some popular options:
- c: bytes
- k: Kilobytes
- M: Megabytes
- G: Gigabytes
- b: 512-byte blocks
To find all files that are exactly
50 bytes, type:
find
/ -size 50c
To find all files less than 50
bytes, we can use this form instead:
find
/ -size -50c
To Find all files more than 700
Megabytes, we can use this command:
find
/ -size +700M
Time
Linux stores time data about access
times, modification times, and change times.
- Access Time: Last time a file was read or written to.
- Modification Time: Last time the contents of the file were modified.
- Change Time: Last time the file's inode meta-data was changed.
We can use these with the
"-atime", "-mtime", and "-ctime" parameters.
These can use the plus and minus symbols to specify greater than or less than,
like we did with size.
The value of this parameter
specifies how many days ago you'd like to search.
To find files that have a
modification time of a day ago, type:
find
/ -mtime 1
If we want files that were accessed
in less than a day ago, we can type:
find
/ -atime -1
To get files that last had their
meta information changed more than 3 days ago, type:
find
/ -ctime +3
There are also some companion
parameters we can use to specify minutes instead of days:
find
/ -mmin -1
This will give the files that have
been modified type the system in the last minute.
Find can also do comparisons against
a reference file and return those that are newer:
find
/ -newer myfile
Finding
by Owner and Permissions
You can also search for files by the
file owner or group owner.
You do this by using the
"-user" and "-group" parameters respectively. Find a file
that is owned by the "syslog" user by entering:
find
/ -user syslog
Similarly, we can specify files
owned by the "shadow" group by typing:
find
/ -group shadow
We can also search for files with
specific permissions.
If we want to match an exact set of
permissions, we use this form:
find
/ -perm 644
This will match files with exactly
the permissions specified.
If we want to specify anything with at
least those permissions, you can use this form:
find
/ -perm -644
This will match any files that have
additional permissions. A file with permissions of "744" would be
matched in this instance.
Filtering
by Depth
For this section, we will create a
directory structure in a temporary directory. It will contain three levels of
directories, with ten directories at the first level. Each directory (including
the temp directory) will contain ten files and ten subdirectories.
Make this structure by issuing the
following commands:
cd
mkdir
-p ~/test/level1dir{1..10}/level2dir{1..10}/level3dir{1..10}
touch
~/test/{file{1..10},level1dir{1..10}/{file{1..10},level2dir{1..10}/{file{1..10},level3dir{1..10}/file{1..10}}}}
cd
~/test
Feel free to check out the directory
structures with ls
and cd to get a handle on how things are
organized. When you are finished, return to the test directory:
cd
~/test
We will work on how to return
specific files from this structure. Let's try an example with just a regular
name search first, for comparison:
find
-name file1
./level1dir7/level2dir8/level3dir9/file1
./level1dir7/level2dir8/level3dir3/file1
./level1dir7/level2dir8/level3dir4/file1
./level1dir7/level2dir8/level3dir1/file1
./level1dir7/level2dir8/level3dir8/file1
./level1dir7/level2dir8/level3dir7/file1
./level1dir7/level2dir8/level3dir2/file1
./level1dir7/level2dir8/level3dir6/file1
./level1dir7/level2dir8/level3dir5/file1
./level1dir7/level2dir8/file1
.
. .
There are a lot of results. If we
pipe the output into a counter, we can see that there are 1111 total results:
find
-name file1 | wc -l
1111
This is probably too many results to
be useful to you in most circumstances. Let's try to narrow it down.
You can specify the maximum depth of
the search under the top-level search directory:
find
-maxdepth num -name query
To find "file1" only in
the "level1" directories and above, you can specify a max depth of 2
(1 for the top-level directory, and 1 for the level1 directories):
find
-maxdepth 2 -name file1
./level1dir7/file1
./level1dir1/file1
./level1dir3/file1
./level1dir8/file1
./level1dir6/file1
./file1
./level1dir2/file1
./level1dir9/file1
./level1dir4/file1
./level1dir5/file1
./level1dir10/file1
That is a much more manageable list.
You can also specify a minimum
directory if you know that all of the files exist past a certain point under
the current directory:
find
-mindepth num -name query
We can use this to find only the
files at the end of the directory branches:
find
-mindepth 4 -name file
./level1dir7/level2dir8/level3dir9/file1
./level1dir7/level2dir8/level3dir3/file1
./level1dir7/level2dir8/level3dir4/file1
./level1dir7/level2dir8/level3dir1/file1
./level1dir7/level2dir8/level3dir8/file1
./level1dir7/level2dir8/level3dir7/file1
./level1dir7/level2dir8/level3dir2/file1
.
. .
Again, because of our branching
directory structure, this will return a large number of results (1000).
You can combine the min and max
depth parameters to focus in on a narrow range:
find
-mindepth 2 -maxdepth 3 -name file
./level1dir7/level2dir8/file1
./level1dir7/level2dir5/file1
./level1dir7/level2dir7/file1
./level1dir7/level2dir2/file1
./level1dir7/level2dir10/file1
./level1dir7/level2dir6/file1
./level1dir7/level2dir3/file1
./level1dir7/level2dir4/file1
./level1dir7/file1
.
. .
Executing
and Combining Find Commands
You can execute an arbitrary helper
command on everything that find matches by using the "-exec"
parameter. This is called like this:
find
find_parameters -exec command_and_params {} \;
The "{}" is used as a
placeholder for the files that find matches. The "\;" is used so that
find knows where the command ends.
For instance, we could find the
files in the previous section that had "644" permissions and modify
them to have "664" permissions:
cd
~/test
find
. -perm 644 -exec chmod 664 {} \;
We could then change the directory
permissions like this:
find
. -perm 755 -exec chmod 700 {} \;
If you want to chain different
results together, you can use the "-and" or "-or" commands.
The "-and" is assumed if omitted.
find
. -name file1 -or -name file9
Find
Files Using Locate
An alternative to using find is the locate command. This command is often quicker and can search the
entire file system with ease.
You can install the command with
apt-get:
sudo
apt-get update
sudo
apt-get install mlocate
The reason locate is faster than
find is because it relies on a database of the files on the filesystem.
The database is usually updated once
a day with a cron script, but you can update it manually by typing:
sudo
updatedb
Run this command now. Remember, the
database must always be up-to-date if you want to find recently acquired or
created files.
To find files with locate, simply
use this syntax:
locate
query
You can filter the output in some
ways.
For instance, to only return files
containing the query itself, instead of returning every file that has the query
in the directories leading to it, you can use the "-b" for only
searching the "basename":
locate
-b query
To have locate only return results
that still exist in the filesystem (that were not remove between the last
"updatedb" call and the current "locate" call), use the
"-e" flag:
locate
-e query
To see statistics about the
information that locate has cataloged, use the "-S" option:
locate
-S
Database
/var/lib/mlocate/mlocate.db:
3,315 directories
37,228 files
1,504,439 bytes in file names
594,851 bytes used to store database
Conclusion
Both find and locate are good ways
to find files on your system. It is up to you to decide which of these tools is
appropriate in each situation.
Find and locate are powerful
commands that can be strengthened by combining them with other utilities
through pipelines. Experiment with filtering by using commands like wc, sort,
and grep.
Linux and Unix find command
Quick links
About find
Syntax
find [-H] [-L] [-P] [-D debugopts] [-Olevel] [path...] [expression]
Description
find locates files on your system. Within each directory
tree specified by the given paths, it evaluates the given expression
from left to right, according to the rules of precedence (see "Operators",
below) until the outcome is known. The outcome is "known" when the
left hand side of the expression is determined to be FALSE for AND operations,
or TRUE for OR operations. At that point find moves on to the next path
until all paths have been searched.
find is a fundamental and extremely powerful tool for
working with the files on your linux system. It can be used on its own to
locate files, or in conjunction with other programs to perform operations on
those files.
Options
The -H, -L and -P options control the
treatment of symbolic
links. Arguments
following these are taken to be names of files or directories to be examined,
up to the first argument that begins with "-", or the argument
"(" or "!". That argument and any following
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. More information on this below).
The arguments in the expression list are also referred to
as "options," but the five "real" options -H, -L,
-P, -D and -O must appear before the first path name, if
they are used at all. A double-dash ("--") can also be used to
signal that any remaining arguments are not options (though ensuring that all
start points begin with either "./" or "/" is
generally safer if you use wildcards in the
list of start points).
-P
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Never follow symbolic links. This is the default. When find
examines or prints information a file, and the file is a symbolic link, the
information used will be taken from the properties of the symbolic link
itself.
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-L
|
Follow symbolic links. When find examines or prints
information about files, the information used will be taken from the
properties 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 subdirectory 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 broken). Using -L causes the -lname and -ilname predicates always to return false. |
-H
|
Do not follow symbolic links, except while processing the
command line arguments. When find examines or prints information about
files, the information used will be taken from the properties of the symbolic
link itself. The only exception to this behaviour is when a file specified on
the command line is a symbolic 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 symbolic 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 specifying -maxdepth 0 would
prevent this).
|
If more than one of -H, -L and -P is
specified, each overrides the others; 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 consideration applies to -newerXY, -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).
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 consideration applies to -newerXY, -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).
-D debugoptions
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Print diagnostic information; this can be helpful to
diagnose problems with why find is not doing what you want. The list
of debug options should be comma separated. Compatibility of the debug
options is not guaranteed between releases of findutils. For a
complete list of valid debug options, see the output of find -D help.
Valid debug options include:
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-Olevel
|
Enables query optimisation.
The find program reorders tests to speed up execution while preserving
the overall effect; that is, predicates with side effects are not reordered
relative to each other. The optimisations performed at each optimisation
level are as follows.
There must not be a space in between -O and the decimal representing the optimization level. The decimals and their meanings are as follows:
The cost-based optimiser has a fixed idea of how likely
any given test is to succeed. In some cases the probability takes account of
the specific nature of the test (for example, -type f is assumed to be
more likely to succeed than -type c). The cost-based optimiser is
currently being evaluated. If it does not actually improve the performance of
find, it will be removed again. Conversely, optimisations that prove
to be reliable, robust and effective may be enabled at lower optimisation
levels over time. However, the default behaviour (i.e. optimisation level 1)
will not be changed in the 4.3.x release series. The findutils test
suite runs all the tests on find at each optimisation level and ensures that
the result is the same.
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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
operators. -and is assumed where the operator is omitted.
If the expression contains no actions other than -prune, -print is performed on all files for which the expression is true.
If the expression contains no actions other than -prune, -print is performed on all files for which the expression is true.
Expression Options
All options always return true. Except for -daystart, -follow
and -regextype, the options affect all tests, including tests specified
before the option. This is because the options are processed when the command
line is parsed, while the tests don't do anything until files are examined. The
-daystart, -follow and -regextype options are different in
this respect, and have an effect only on tests which appear later in the
command line. 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.
-d
|
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-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. The -delete action also implies -depth.
|
-follow
|
This is an older way to do the same thing as -L. It
is now deprecated; you should use the -L option instead.
This option dereferences symbolic links and 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 -newerXY, -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 help message, and exit.
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-ignore_readdir_race
|
Normally, find will give an error message when it
cannot 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 paths
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.
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-maxdepth levels
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Descend at most levels (a non-negative integer) levels
of directories below the command line arguments. -maxdepth 0 means
only apply the tests and actions to the paths specified on the command
line, and do not descend into subdirectories at all.
|
-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.
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-mount
|
Don't descend directories on other filesystems. An
alternate name for -xdev. This option is provided for compatibility
with some other versions of find.
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-noignore_readdir_race
|
Turns off the effect of -ignore_readdir_race.
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-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.
If you are using a standard linux filesystem, you should not need to use this option. |
-regextype type
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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.
If you're using a specific style of regular expression syntax, you may need to specify this option. Otherwise, it should be unnecessary. |
-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
Some tests, for example -newerXY and -samefile,
allow comparison between the file currently being examined and some reference
file specified on the command line. When these tests are used, the
interpretation of the reference file is determined by the options -H, -L
and -P and any previous -follow, but the reference file is only
examined once, at the time the command line is parsed. If the reference file
cannot be examined (for example, the stat system call fails for it), an
error message is issued, and find exits with a nonzero status.
Where n is used as a numeric argument, it can be specified as:
Where n is used as a numeric argument, it can be specified as:
+n
|
for greater than n;
|
-n
|
for less than n;
|
n
|
for exactly n.
|
Tests are as follows:
-amin n
|
Returns true is a file was last accessed n minutes
ago.
|
||||||||||||||||
-anewer file
|
Returns true if a 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
|
Returns true if a 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
|
Returns true if a file's status was last changed n
minutes ago.
|
||||||||||||||||
-cnewer file
|
Returns true if a file's status was last changed more
recently than file was modified. 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
|
Returns true if a 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
|
Returns true if a file is empty (contains nothing) and is
either a regular file or a directory.
|
||||||||||||||||
-executable
|
Matches files which are executable and directories which
are searchable (in a file name resolution sense). This takes into account
access control lists and other permissions artefacts which the -perm
test ignores. This test makes use of the access system call, and so
can be fooled by NFS
servers which do UID mapping (or root-squashing),
since many systems implement access in the client's kernel and so
cannot make use of the UID mapping information held on the server. Because
this test is based only on the result of the access system call, there is no
guarantee that a file for which this test succeeds can actually be executed.
|
||||||||||||||||
-false
|
When used as part of an expression, -false always
evaluates as false.
|
||||||||||||||||
-fstype type
|
Returns true if a 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.
|
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-gid n
|
Returns true if a file's numeric group ID is n.
|
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-group gname
|
Returns true if a file belongs to group gname
(numeric group IDs are allowed).
|
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-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 expansion by the shell, an initial '.'
can be matched by '*'. That is, find -name *bar will match the
file '.foobar'. Please note that you should always quote patterns,
otherwise the shell will expand any wildcard characters in
them.
|
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-inum n
|
Returns true if a 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 deprecated, so you should no longer use it.
|
||||||||||||||||
-iregex pattern
|
Like -regex, but the match is case-insensitive.
|
||||||||||||||||
-iwholename pattern
|
Like -wholename, but the match is case-insensitive.
|
||||||||||||||||
-links n
|
Returns true if a file has n links.
|
||||||||||||||||
-lname pattern
|
Returns true if a file is a symbolic link whose contents
match shell pattern pattern. 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
|
Returns true if the file's data was last modified n
minutes ago.
|
||||||||||||||||
-mtime n
|
Returns true if a file's data was last modified n *
24 hours ago. See the -atime option to understand how rounding affects
the interpretation of file modification times.
|
||||||||||||||||
-name pattern
|
Returns true if the base of a 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. To ignore a directory and the files under it,
use -prune; see an example in the description of -path. 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 library
function. Don't forget to enclose the pattern in quotes in order to protect
it from expansion by the shell.
|
||||||||||||||||
-newer file
|
Returns true if a file was modified more recently than the
file file. If file is a symbolic link and the -H option
or the -L option is in effect, the modification time of the file it
points to is always used.
|
||||||||||||||||
-newerXY reference
|
Compares the timestamp of the
current file with reference. The reference argument is normally
the name of a file (and one of its timestamps is used for the comparison) but
it may also be a string describing an absolute time. X and Y
are placeholders for other letters, and these letters select which time
belonging to how reference is used for the comparison.
Some combinations are invalid; for example, it is invalid
for X to be t. Some combinations are not implemented on all
systems; for example B is not supported on all systems. If an invalid
or unsupported combination of XY is specified, a fatal error results.
Time specifications are interpreted as for the argument to the -d
option of GNU date.
If you try to use the birth time of a reference file, and the birth
time cannot be determined, a fatal error message results. If you specify a
test which refers to the birth time of files being examined, this test will
fail for any files where the birth time is unknown.
|
||||||||||||||||
-nogroup
|
Returns tue if no existing group corresponds to file's
numeric group ID.
|
||||||||||||||||
-nouser
|
Returns true if no existing user corresponds to file's
numeric user ID.
|
||||||||||||||||
-path pattern
|
Returns true if a file name
matches shell pattern pattern. The metacharacters do not treat '/'
or '.' specially; so, for example,
find . -path "./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 . -path ./src/emacs -prune -o -print
Note that the pattern match
test applies to the whole file name, starting from one of the start points
named on the command line. It would only make sense to use an absolute pathname
here if the relevant start point is also an absolute path. This means that
this command will never match anything:
find bar -path /foo/bar/myfile -print |
||||||||||||||||
-perm mode
|
Returns true if a 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 permission 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.
|
||||||||||||||||
-perm -mode
|
Returns true if all of the permission bits of 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.
|
||||||||||||||||
-perm /mode
|
Returns true if any of the permission bits of 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.
If no permission bits in mode are set, this test matches any file.
|
||||||||||||||||
-perm +mode
|
Deprecated; this is the old way of searching for files
with any of the permission bits in mode. You should use -perm /mode
instead. Trying to use the '+' syntax with symbolic modes will yield
unexpected results.
|
||||||||||||||||
-readable
|
Matches files which are readable. This takes into account access control lists
and other permissions factors which the -perm test ignores. This test
makes use of the access
system call, and so can be fooled by NFS servers which do
UID mapping (or root-squashing), since many systems implement access
in the client's kernel
and so cannot make use of the UID mapping information held on the server.
|
||||||||||||||||
-regex pattern
|
Returns true if a filename matches the regular expression pattern.
This is a match on the whole path, not just the filename. For example, to
match a file named './fubar3', you can use the regular expression '.*bar.'
or '.*b.*3', but not 'f.*r3' (because the complete path does
not begin with an f). The regular expressions understood by find
are by default Emacs
regular expressions, but this can be changed with the -regextype
option (see above).
|
||||||||||||||||
- samefile name
|
Returns true if a file refers to the same inode as name.
When -L is in effect, this can include symbolic links.
|
||||||||||||||||
-size [-|+]n[cwbkMG]
|
Returns true if a file uses n
units of space on the disk. If preceded by a minus sign ("-"),
matches files which use less space; if preceded by a plus sign ("+"),
matches files which use more. The following suffixes can be used to
abbreviate units:
The size does not count indirect blocks, but it does count
blocks in sparse files that are not actually allocated. You should note 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 than the behaviour of -ls.
|
||||||||||||||||
-true
|
When used in an expression, -true always returns true.
|
||||||||||||||||
-type c
|
Returns true if a file is of
type c:
|
||||||||||||||||
-uid n
|
Returns true if a file's numeric user ID is n.
|
||||||||||||||||
-used n
|
Returns true if a file was last accessed n days
after its status was last changed.
|
||||||||||||||||
-user uname
|
Returns true if a file is owned by user uname
(numeric user IDs are allowed).
|
||||||||||||||||
-wholename pattern
|
Functionally the same as -path. This alternative is
less portable than -path, however; for greatest compliance across
different types of systems, you should use -path instead.
|
||||||||||||||||
-writable
|
Matches files which are writable. This takes into account
access control lists and other permissions factors which the -perm
test ignores. This test makes use of the access system call, and so
can be fooled by NFS servers which do UID mapping (or root-squashing), since
many systems implement access in the client's kernel and so cannot make use
of the UID mapping information held on the server.
|
||||||||||||||||
-xtype c
|
The same as -type unless the file is a symbolic
link. For symbolic links: if the -H or -P option was specified,
returns true if the file is a link to a file of type c; if the -L
option has been given, returns 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 matched files; returns true if removal succeeded.
If the removal failed, an error message is issued. If -delete fails, find's
exit status will be nonzero (when it eventually exits). Use of -delete
automatically turns on the -depth option.
Don't forget that the find command line is evaluated as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. When testing a find command line that you later intend to use with -delete, you should explicitly specify -depth in order to avoid later surprises. Because -delete implies -depth, you cannot usefully use -prune and -delete together. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-exec command ;
|
Execute command on each matched file; returns true
if 0 is returned as the exit status of command. All following
arguments to find are taken to be arguments to the command until a
semicolon (';') 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. The
specified command is run once for each matched file. The command is executed
in the starting directory. There are unavoidable security problems
surrounding use of -exec; you should use the -execdir option
instead.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-exec command {} +
|
This variant of the -exec action 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 invocations 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 subdirectory 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" (where the
behavior is determined by an unpredictable order of system operations) during
resolution of the paths to the matched files. As with the -exec
action, 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 subdirectory. If you use this option,
you must ensure that your $PATH environment variable does not
reference '.'; otherwise, an attacker can run any commands they like
by leaving an appropriately-named file in a directory in which you will run -execdir.
The same applies to having entries in $PATH which are empty or which
are not absolute directory names.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-fls file
|
Returns true; behaves like -ls, but writes to file
like -fprint. The output file is always created, even if no match is
found.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-fprint file
|
Returns true; prints 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.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-fprint0 file
|
Returns true; like -print0 but writes to file
like -fprint. The output file is always created, even if no match is
found.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-fprintf file format
|
Returns true; like -printf, but writes to file
like -fprint. The output file is always created, even if the predicate
is never matched.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-ls
|
Returns true; lists current file in ls -dils format
(see ls for
details) on standard output. The block counts are of 1K blocks, unless the environment variable
POSIXLY_CORRECT is set, in which case 512-byte blocks are used.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-ok command ;
|
Like -exec, but asks the user first. If the user
agrees, find runs the command. Otherwise it simply returns false. If
the command is run, its standard input is redirected from /dev/null.
The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the 'POSIXLY_CORRECT' environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables 'LC_CTYPE' (character classes) and 'LC_COLLATE' (character ranges and equivalence classes). |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-okdir command ;
|
Like -execdir but asks the user first in the same
way as for -ok. If the user does not agree, simply returns false. If
the command is run, its standard input is redirected from /dev/null.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-print
|
Returns true; prints 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 consider using the -print0 option instead of -print.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-print0
|
Returns true; prints 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 programs that process the find output.
This option corresponds to the -0 option of xargs.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-printf format
|
Returns true; prints 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 '\' character
followed by any other character is treated as an ordinary character, so they
both are printed.
A '%' character followed by any other character is
discarded, but the other character is printed (but don't rely on this, as
further format characters may be introduced). A '%' at the end of the
format argument causes undefined behaviour since there is no following
character. In some locales, it may hide your door keys, while in others it
may remove the final page from the novel you are reading.
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 alignment of a field from right-justified (which is the default) to left-justified. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-prune
|
True; if the file is a directory, do not descend
into it. If -depth is given, false; no effect. Because -delete
implies -depth, you cannot usefully use -prune and -delete
together.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-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.
|
Handling 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' owners but
which cannot be used to send arbitrary data to the terminal, 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. The setting of the
'LC_CTYPE' environment variable is used to determine which characters
need to be quoted.
|
-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.
Operators
The following find operators are listed in order of
increasing precedence:
( expr )
|
Force precedence. Since parentheses are special to the
shell, you will normally need to quote them. For instance, you will probably
need to specify '\(...\)' instead of '(...)'.
|
! expr
|
Returns true if expr is false. This character will
also usually need protection from interpretation by the shell.
|
-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"; in other words, 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
|
Boolean OR; in other words, expr2 is not evaluated
if expr1 is true.
|
expr1 -or expr2
|
Same as expr1 -o expr2, but not POSIX
compliant.
|
expr1 , expr2
|
Separating two expressions with a comma treats them as a
list: both expr1 and expr2 are always evaluated. The value of expr1
is discarded in the return value; 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.
|
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, this variable's value
overrides the values of all the other internationalization variables.
|
LC_COLLATE
|
The POSIX standard specifies that this variable affect the
pattern matching to be used for the -name option. GNU find uses
the fnmatch library function, and so support for 'LC_COLLATE'
depends on the system library. This variable also affects the interpretation
of the response to -ok; while the 'LC_MESSAGES' variable
selects the actual pattern used to interpret the response to -ok, the
interpretation of any bracket expressions in the pattern will be affected by
'LC_COLLATE'.
|
LC_CTYPE
|
This variable affects the treatment of character classes
used in regular expressions and also with the -name test, if the
system's fnmatch library function supports this. This variable also
affects the interpretation of any character classes in the regular
expressions used to interpret the response to the prompt issued by -ok.
The 'LC_CTYPE' environment variable will also affect which characters
are considered to be unprintable when filenames are printed.
|
LC_MESSAGES
|
Determines the locale to be used for internationalised
messages. If the 'POSIXLY_CORRECT' environment variable is set, this
also determines the interpretation of the response to the prompt made by the -ok
action.
|
NLSPATH
|
Determines the location of the internationalisation
message catalogues.
|
PATH
|
Affects the directories which are searched to find the
executables 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. Otherwise
they are units of 1024 bytes.
Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. |
TZ
|
Affects the time zone used for some of the time-related
format directives of -printf and -fprintf.
|
Examples
find
When using linux, running the find command without any
options will locate and print a list of every file in and beneath the current
directory. This includes all files in all subdirectories of the current
directory.
find .
Same as the above command. The "." explicitly
tells find that you want the search to begin in the current directory.
find . /home/jeff /home/stacy
Locate and print all files and directories in and beneath three
different starting directories: the current directory, /home/jeff, and /home/stacy.
find /usr/bin /usr/lib -name '*zip*'
Locate and print all files and directories in and beneath either
of the directories /usr/bin and /usr/lib which contains the text
"zip" anywhere in the file or directory name.
find /home/jeff/fruit | grep 'apple'
This command tells find to locate and print a complete list
of all files in and beneath the directory /home/jeff/fruit, and to pipe this listing to grep,
which filters out any filename which does not contain the text "apple".
find . -name 'apple'
Locate and print a list of any file in or below the current
directory whose name is exactly "apple", all lower case
letters.
find . -iname 'apple'
Locate and print a list of any file in or below the current
directory whose name is "apple", but match the letters
case-insensitively. Therefore, files or directories named "Apple",
"ApplE", and "ApPLe" will all be listed by
this command.
find . -name 'apple' -type f
Locate and print a list of files in or below the current directory
whose name is "apple"; do not display directories, sockets, or
other non-regular file types.
find . -name 'apple' -type d
Locate a print a list of directories in or below the current
directory whose name is "apple"; do not display regular files,
or file types other than directory entries.
find . -group dev
Locate and print a list of any file in or below the current
directory whose owning group is the dev group.
find . -L
Locate and print a list of any file in or below the current
directory, and follow symbolic links. In
other words, display information about the file a symbolic link links to,
rather than information about the symlink itself.
find . -atime +1
Locate and print a list of any file in or below the current
directory that was last accessed more than 1 day ago.
find . -atime -1
Locate and print a list of any file in or below the current
directory that was last accessed less than 1 day ago.
find . -amin +5
Locate and print a list of any file in or below the current
directory that was modified more than 5 minutes ago.
find . -amin -5
Locate and print a list of any file in or below the current
directory that was modified fewer than 5 minutes ago.
find . -perm 754
Locate and print a list of any file in or below the current
directory whose octal
permission bits are 755 (user can read, write, and execute; owning group
members can read and execute; others can read only). For more information about
permission bits, see chmod.
find . -perm u=rwx,g=rx,o=r
Same as the above command, but uses a symbolic representation of
the permission bits. Note that the symbolic notation uses a comma separator and
contains no spaces.
find . -size +1M -type f
Locate and print a list of any regular file in or below the
current directory whose size is greater than 1 megabyte.
find . -size -5G -type f
Locate and print a list of any regular file in or below the
current directory whose size is less than 5 gigabytes.
find . -user jeff
Locate and print a list of any file or directory in or below the
current directory owned by the user jeff.
find . -size +1G -exec mv '{}' ~/bigfiles \;
Locate any files in or below the current directory whose size is
greater than 1 gigabyte, and execute the mv command on
them, moving them into the directory bigfiles in your home directory.
The {} indicates where in the command the name of the matched file
should be placed; it must be enclosed in quotes to protect it from being
misinterpreted by the shell. Similarly, the semicolon which ends the command
must be escaped with a backslash ("\;").
find . -size +1G -print0 | xargs -0 -I '{}' mv '{}' ~/bigfiles
Locate any files in or below the current directory whose size is
greater than 1 gigabyte, then pipe that list to the xargs
command, which uses the mv
command to move each one of those files into the directory bigfiles in
your home directory. This is similar to the above command, but better for
several reasons. First, it uses the -print0 option to tell find
to create its list separating each filename with a null character rather
than a newline;
this makes the list difficult for a human to read, but has the advantage of
making it easier for another program to parse. You should always use -print0
when piping output to xargs.
Using xargs to execute commands on every file found is generally better than using find's -exec option because of the more efficient way xargs threads each individual command that it spawns.
The -0 argument to xargs tells it to expect the null character as the filename separator (which we specified with find's -print0 option).
The -I '{}' option tells xargs to replace "{}" with the name of each file it finds. We then form our command using {} where we want the filename to appear. We enclose it in single quotes to protect it from the shell.
xargs does not expect a semicolon at the end of the command, unlike find -exec, so it is not included in this command.
Using xargs to execute commands on every file found is generally better than using find's -exec option because of the more efficient way xargs threads each individual command that it spawns.
The -0 argument to xargs tells it to expect the null character as the filename separator (which we specified with find's -print0 option).
The -I '{}' option tells xargs to replace "{}" with the name of each file it finds. We then form our command using {} where we want the filename to appear. We enclose it in single quotes to protect it from the shell.
xargs does not expect a semicolon at the end of the command, unlike find -exec, so it is not included in this command.
find . -size +1G -ok mv '{}' ~/bigfiles \;
Using -ok is the same as using -exec, but you will
be asked for confirmation before each command is executed.
find . -name '*.jpg' -o -name '*.gif'
Locate any files in or below the current directory whose suffix is
".jpg" or ".gif". The -o option
functions as a boolean
OR operator; if either of the conditions are true, the file will be included in
the list.
find . -maxdepth 2 -name '*.jpg'
Locate any files in or below the current directory whose suffix is
".jpg", but limit subdirectory traversal to 2 levels
beneath the current directory. Any subdirectories 3 or more levels deep will
not be searched.
find . ! -name '*.jpg'
Locate any files in or below the current directory whose suffix is
not ".jpg". The exclamation mark ("!")
functions as a boolean NOT operator; it lists only files for which the
condition is false.
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. The -name test comes before the -type test in
order to avoid having to call stat on every file.
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 /sbin /usr/sbin -executable ! -readable
Search for files in your superuser binary directories, /sbin
and /usr/sbin, which are executable but not readable.
Suppressing Error Messages When Using find
One last tip for using find: you will receive an error
message if find encounters a file or directory you don't have access to
view. The error message will look like this:
find: `./tmp/sysfile-PKdhtXMmr18n': Permission denied
You might not want these messages in your output; they can make it
difficult to parse your actual find results.
For these examples, we'll assume you're using bash as your shell, which is the default under linux. Let's say your command is this simple one:
For these examples, we'll assume you're using bash as your shell, which is the default under linux. Let's say your command is this simple one:
find .
If the results of this command are giving you "Permission
denied" errors, the simplest way to filter them out is to send them
all to /dev/null, which is the device on linux which points to nowhere.
Your command would look like this:
find . 2>/dev/null
Here, 2> is a special operator in bash which
means "redirect standard error". This will effectively hide all error
messages from find's output.
You might not want to hide every error message, though. What if there's another error of some kind? You don't want to suppress those messages too. In that case, you can use this command instead:
You might not want to hide every error message, though. What if there's another error of some kind? You don't want to suppress those messages too. In that case, you can use this command instead:
find . 2>&1 | grep -v 'Permission denied'
Here, 2> tells bash to redirect standard error,
and &1 tells it to use standard output as the destination. This
redirects all error messages issued by find to standard output; this
will look the same on your terminal screen, but by merging them with standard
output, we have made them filterable by grep. So we then pipe the output
of find to grep, which matches the inverse (-v) of our
string, 'Permission denied'. The result is that it displays any line
which does not contain that string. This allows you to view your results
without any pesky "Permission denied" error messages.
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