Editing Find (Unix) (section)

==Find syntax==
<syntaxhighlight lang="console">
$ find [-H|-L] path... [operand_expression...]
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The two options control how the <code>find</code> command should treat symbolic links. The default behaviour is never to follow symbolic links. The {{code|-L}} flag will cause the <code>find</code> command to follow symbolic links. The {{code|-H}} flag will only follow symbolic links while processing the command line arguments. These flags are specified in the POSIX standard for <code>find</code>.<ref name=sus>{{man|cu|find|SUS|find files}}</ref> A common extension is the {{code|-P}} flag, for explicitly disabling symlink following.<ref name=fbsd>{{man|1|find|FreeBSD}}</ref><ref>{{man|1|find|Linux}}</ref>

At least one path must precede the expression. <code>find</code> is capable of interpreting [[Wildcard character|wildcards]] internally and commands must be quoted carefully in order to control [[Glob (programming)|shell globbing]].

Expression elements are separated by the [[command-line argument]] boundary, usually represented as whitespace in shell syntax. They are evaluated from left to right. They can contain logical elements such as AND ({{code|-and}} or {{code|-a}}) and OR ({{code|-or}} or {{code|-o}}) as well as predicates (filters and actions).

GNU <code>find</code> has a large number of additional features not specified by POSIX.

===Predicates===
{{anchor|type filters}}

Commonly-used primaries include:

* <code>-name ''pattern''</code>: tests whether the file name matches the shell-glob pattern given.
* <code>-type ''type''</code>: tests whether the file is a given type. [[Unix file types]] accepted include:
** <code>b</code>: [[Device file|block device (buffered)]];
** <code>c</code>: [[Device file|character device (unbuffered)]];
** <code>d</code>: ''[[Directory (computing)|directory]]'';
** <code>f</code>: ''[[regular file]]'';
** <code>l</code>: [[symbolic link]];
** <code>p</code>: [[named pipe]];
** <code>s</code>: [[Unix domain socket|socket]];
** <code>D</code>: [[Doors (computing)|door]].
* <code>-print</code>: always returns true; prints the name of the current file plus a newline to the [[stdout]].
* <code>-print0</code>: always returns true; prints the name of the current file plus a null character to the [[stdout]]. Not required by POSIX.
* <code>-exec ''program'' ''[arguments...]'' ;</code>: runs ''program'' with the given arguments, and returns true if its exit status was 0, false otherwise. If ''program'', or an argument is '''{}''', it will be replace by the current path (if ''program'' is '''{}''', <code>find</code> will try to run the current path as an executable). POSIX doesn't specify what should happen if multiple '''{}''' are specified. Most implementations will replace all '''{}''' with the current path, but that is not standard behavior.
* <code>-exec ''program'' ''[arguments...]'' {} +</code>: always returns true; run ''program'' with the given arguments, followed by as many paths as possible (multiple commands will be run if the maximum command-line size is exceeded, like for [[xargs]]).<ref name=sus/>
* <code>-ok ''program'' ''[arguments...]'' ;</code>: for every path, prompts the user for confirmation; if the user confirms (typically by entering ''y'' or ''yes''), it behaves like <code>-exec ''program [arguments...]'' ;</code>, otherwise the command is not run for the current path, and false is returned.
* <code>-maxdepth</code>: Can be used to limit the directory depth to search through. For example, <code>-maxdepth 1</code> limits search to the current directory.

If the expression uses none of <code>-print0</code>, <code>-print</code>, <code>-exec</code>, or <code>-ok</code>, find defaults to performing <code>-print</code> if the conditions test as true.

===Operators===
Operators can be used to enhance the expressions of the find command. Operators are listed in order of decreasing precedence:
* <code>( expr )</code>: forces precedence;
* <code>! expr</code>: true if {{code|expr}} is false;
* <code>expr1 expr2</code> (or <code>expr1 -a expr2</code>): AND. {{code|expr2}} is not evaluated if {{code|expr1}} is false;
* <code>expr1 -o expr2</code>: OR. {{code|expr2}} is not evaluated if {{code|expr1}} is true.

<syntaxhighlight lang="console">
$ find . -name 'fileA_*' -o -name 'fileB_*'
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This command searches the current working directory tree for files whose names start with {{code|fileA_}} or {{code|fileB_}}. We quote the {{code|fileA_*}} so that the shell does not expand it.

<syntaxhighlight lang="console">
$ find . -name 'foo.cpp' '!' -path '.svn'
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This command searches the current working directory tree except the subdirectory tree ".svn" for files whose name is "foo.cpp". We quote the <code>!</code> so that it's not interpreted by the shell as the history substitution character.