linux command

find

Linux Command – find ใช้ในการค้นหา file หรือ directory ด้วยเงือนไขต่างๆ เช่น ชื่อ, ขนาด, เวลา

 

คำสั่ง

1. ค้นหาด้วยชื่อ file

find -name <name>

find -name "query"

ไม่สนใจตัวเล็ก ตัวใหญ่ (case sensitive)

find -iname "query"

หา file ทั้งหมดแบบยกเว้น

find -not -name "query_to_avoid"
find \! -name "query_to_avoid"

 

2. ค้นหาตามชนิด file

find -type <type>

find -type type_descriptor query

ชนิดของ file

  • f: file ปกติ
  • d: directory
  • l: symbolic link
  • c: character devices
  • b: block devices

กำหนด path ที่จะค้นหาได้ด้วยการใส้ path ไว้ใน expression แรก

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
. . .

สามารถค้นหาแบบ widecard ด้วย (*)

 

3. ค้นหาตามขนาด file

 

find <path> -size <size>

  • c: bytes
  • k: Kilobytes
  • M: Megabytes
  • G: Gigabytes
  • b: 512-byte blocks

50 bytes

find / -size 50c

น้อยกว่า 50 bytes

find / -size -50c

มากกว่า 700 Megabytes

find / -size +700M

 

4. ค้นหาด้วยเวลาของ file

เวลา file มี 3 แบบคือ

  • Access Time: เวลาครั้งสุดท้ายที่ read/write
  • Modification Time: เวลาครั้งสุดท้ายที่มีการแก้ไขข้อมูลข้างใน
  • Change Time: เวลารครั้งสุดท้ายที่มีการแก้ไขข้อมูลภายนอก เช่น owner, permission

file ที่มีการแก้ไขข้อมูลภายใน 1 วันที่แล้ว

find / -mtime 1

file ที่มีการ read/write ข้อมูลภายในน้อยกว่า 1 วันที่แล้ว

find / -atime -1

file ที่มีการแก้ไขข้อมูลภายนอกมากกว่า 3 วันที่แล้ว

find / -ctime +3

file ที่มีการแก้ไขข้อมูลภายในน้อยกว่า 1 นาทีที่แล้ว

find / -mmin -1

 

file ล่าสุดด้วยการเปรียบเทียบข้อมูลเวลากับ file อื่นๆทั้งหมด

find / -newer myfile

 

โครงสร้างคำสั่ง

  find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression]

 

รายละเอียด

เป็นคำสั่งที่ใช้ในการค้นหา file หรือ directory ด้วยเงือนไขต่างๆ เช่น ชื่อ, ขนาด, เวลา

 

Option

 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 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).

 This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five
 `real' options -H, -L, -P, -D and -O must appear before the first path name, if 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 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 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). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. 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 shall 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 of course -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 com‐
 mand 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 sym‐
 bolic 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
 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. Com‐
 patibility 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

 help Explain the debugging options

 tree Show the expression tree in its original and optimised form.

 stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls.

 opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option.

 rates Prints a summary indicating how often each predicate succeeded or failed.

 -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.

 0 Equivalent to optimisation level 1.

 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for
 example -name and -regex) are performed first.

 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many mod‐
 ern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you
 use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equiv‐
 alent to -false.

 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and
 more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to suc‐
 ceed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier.

 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 perfor‐
 mance 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.

EXPRESSION
 The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files
 that were matched. An expression is composed of a sequence of things:

 Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is
 empty.

 Actions
 Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The
 -print action for example prints the name of the current file on the standard output.

 Global options
 Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes
 find traverse the file system in a depth-first order.

 Positional options
 Positional optiona affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the
 regular expression dialect for regulat expressions occurring later on the command line.

 Operators
 Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing,
 -a is assumed.

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

 The -delete action also acts like an option (since it implies -depth).

 POSITIONAL OPTIONS
 Positional options always return true. They affect only tests occurring later on the command line.

 -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.

 -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 -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.

 -regextype type
 Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use
 -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression.

 -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. If a warning message relating to command-line usage is produced, the exit sta‐
 tus of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active.

 GLOBAL OPTIONS
 Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should specified on the
 command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning
 message explaining that this can be confusing.

 The global options occur after the list of start points, and so are not the same kind of option as -L, for example.

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

 -depth Process each directory's contents before the directory itself. The -delete action also implies -depth.

 -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 directories below the starting-points. -maxdepth 0
 means only apply the tests and actions to the starting-points themselves.

 -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 starting-points.

 -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.

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

 -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(2) system call fails for it), an error message is issued, and find exits with a nonzero
 status.

 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 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
 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.

 -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 permis‐
 sions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squash‐
 ing), since many systems implement access(2) 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(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed.

 -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. The pattern `*foo*` will
 also match a file called '.foobar'.

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

 -ipath pattern
 Like -path. but the match is case insensitive.

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

 -iwholename pattern
 See -ipath. This alternative is less portable than -ipath.

 -links n
 File has n links.

 -lname pattern
 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
 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. Because the leading directories are removed, the file names considered for
 a match with -name will never include a slash, so `-name a/b' will never match anything (you probably need to use -path instead). A warning is issued if you try to do this,
 unless the environment variable POSIXLY_CORRECT is set. The metacharacters (`*', `?', and `[]') match a `.' at the start of the base name (this is a change in findu‐
 tils-4.2.2; see section STANDARDS CONFORMANCE below). 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(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 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
 Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters:

 a The access time of the file reference
 B The birth time of the file reference
 c The inode status change time of reference
 m The modification time of the file reference
 t reference is interpreted directly as a time

 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 sys‐
 tems. 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
 No group corresponds to file's numeric group ID.

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

 -path pattern
 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 abso‐
 lute path name 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
 Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a
 slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX
 find and will be in a forthcoming version of the POSIX standard.

 -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 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. 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 you 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 EXAM‐
 PLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of
 -perm -000).

 -perm +mode
 This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead.

 -readable
 Matches files which are readable. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the
 access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so
 cannot make use of the UID mapping information held on the server.

 -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, rounding up. 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.

 The + and - prefixes signify greater than and less than, as usual. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size
 -1048576c. The former only matches empty files, the latter matches files from 1 to 1,048,575 bytes.

 -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
 See -path. This alternative is less portable than -path.

 -writable
 Matches files which are writable. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the
 access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) 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, 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.

 -context pattern
 (SELinux only) Security context of the file matches glob pattern.

 ACTIONS
 -delete
 Delete files; 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.

 Warnings: 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; 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 section
 for examples of the use of the -exec option. 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 the -exec action; 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. If find encounters an error, this can sometimes cause an imme‐
 diate exit, so some pending commands may not be run at all. This variant of -exec always returns true.

 -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 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 appro‐
 priately-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.
 If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or
 the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0.

 -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 infor‐
 mation 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 infor‐
 mation about how unusual characters in filenames are handled.

 -ls True; list current file in ls -dils format 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. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled.

 -ok command ;
 Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return 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 ask the user first in the same way as for -ok. If the user does not agree, just 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 possibil‐
 ity 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 FILE‐
 NAMES section for information about how unusual characters in filenames are handled.

 -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 programs 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.

 \0 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, with fractional part.

 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 (00.00 .. 61.00). There is a fractional part.

 T time, 24-hour (hh:mm:ss.xxxxxxxxxx)

 + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be
 affected by setting the TZ environment variable). The seconds field includes a fractional part.

 X locale's time representation (H:M:S). The seconds field includes a fractional part.

 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 (Sunday..Saturday)

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

 B locale's full month name, variable length (January..December)

 c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no
 fractional part in the seconds field.

 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/512, 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 starting-point.

 %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 element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands
 to ".".

 %H Starting-point 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 starting-point under which it was found removed.

 %s File's size in bytes.

 %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent.
 However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. The value used for
 BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a
 file's sparseness is assumed to be 1.0.

 %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

 %Z (SELinux only) file's security context.

 %{ %[ %(
 Reserved for future use.

 A `%' character followed by any other character is discarded, but the other character is printed (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.

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

 -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.

 OPERATORS
 Listed in order of decreasing precedence:

 ( expr )
 Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this pur‐
 pose: `\(...\)' instead of `(...)'.

 ! expr 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"; 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 search‐
 ing 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.

 Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This
 means that find . -name afile -o -name bfile -print will never print afile.

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 char‐
 acters 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 new‐
 line 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. This may change in a future release.

STANDARDS CONFORMANCE
 For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. 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 interpretation 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 according to the "yes" and "no" patterns selected by setting the `LC_MESSAGES' environment variable. When the `POSIXLY_COR‐
 RECT' environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_lang‐
 info(3), in particular YESEXPR and NOEXPR. When `POSIXLY_CORRECT' is not set, the patterns are instead taken from find's own message catalogue.

 -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.

 -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward-compati‐
 bility.

 

กลุ่มคำสั่ง

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), whereis, which

 

Reference:

คำสั่ง Unix – Linux Command

Linux, Unix

 

Author: Suphakit Annoppornchai

Credit: https://saixiii.com

4 Thoughts to “find – Linux Command คำสั่งใช้ในการค้นหา file หรือ directory”

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