find.html

unix 下的C开发手册,还用详细的例程。

by writing to standard error as described in the STDERR section.
If the response on standard input is affirmative,
the utility will be invoked.
Otherwise, the command will not be invoked
and the value of the
<b>-ok</b>
operand will be false.
<dt><b>-print</b>
<dd>The primary always will evaluate as true; it will cause
the current pathname to be written to standard output.
<dt><b>-newer&nbsp;</b><i>file</i>
<dd>
The primary will evaluate as true
if the modification time of the current file
is more recent than the modification time of the
file named by the pathname
<i>file</i>.
<dt><b>-depth</b>
<dd>The primary always will evaluate as true; it will cause
descent of the directory hierarchy to be done
so that all entries in a directory are acted on
before the directory itself.
If a
<b>-depth</b>
primary is not specified, all entries in a directory
will be acted on after the directory itself.
If any
<b>-depth</b>
primary
is specified, it will apply to the entire expression even if the
<b>-depth</b>
primary would not normally be evaluated.

</dl>
<p>
The primaries can be combined using the following operators
(in order of decreasing precedence):
<dl compact>

<dt>(<dd>
True if
<i>expression</i>
is true.

<dt><b>! </b><i>expression</i><dd>
Negation of a primary; the unary NOT operator.

<dt><i>expression&nbsp;</i><b>[-a]&nbsp;</b><i>expression</i><dd>
Conjunction of primaries; the AND
operator will be implied by the juxtaposition
of two primaries or made explicit by the optional
<b>-a</b>
operator.
The second expression will not be evaluated if the first
expression is false.

<dt><i>expression </i><b>-o </b><i>expression</i><dd>
Alternation of primaries; the OR operator.
The second expression will not be evaluated if
the first expression is true.

</dl>
<p>
If no
<i>expression</i>
is present,
<b>-print</b>
will be used as the expression.
Otherwise, if the given expression does not contain
any of the primaries
<b>-exec</b>,
<b>-ok</b>
or
<b>-print</b>,
the given expression will be effectively replaced by:
<pre>
<code>
( <i>given_expression</i> ) -print
</code>
</pre>
<p>
The
<b>-user</b>,
<b>-group</b>
and
<b>-newer</b>
primaries each will evaluate their respective arguments only once.
</blockquote><h4><a name = "tag_001_014_743">&nbsp;</a>STDIN</h4><blockquote>
If the
<b>-ok</b>
primary is used, the response will be read from the standard input.
An entire line will be read as the response.
Otherwise, the standard input will not be used.
</blockquote><h4><a name = "tag_001_014_744">&nbsp;</a>INPUT FILES</h4><blockquote>
None.
</blockquote><h4><a name = "tag_001_014_745">&nbsp;</a>ENVIRONMENT VARIABLES</h4><blockquote>
The following environment variables affect the execution of
<i>find</i>:
<dl compact>

<dt><i>LANG</i><dd>Provide a default value for the internationalisation variables
that are unset or null.
If
<i>LANG</i>
is unset or null, the corresponding value from the
implementation-dependent default locale will be used.
If any of the internationalisation variables contains an invalid setting, the
utility will behave as if none of the variables had been defined.

<dt><i>LC_ALL</i><dd>
If set to a non-empty string value,
override the values of all the other internationalisation variables.

<dt><i>LC_COLLATE</i><dd>
Determine the locale for the
behaviour of ranges, equivalence classes
and multi-character collating elements
used in the pattern matching notation for the
<b>-n</b>
option and in the extended regular expression defined for the
<b>yesexpr</b>
locale keyword in the LC_MESSAGES category.

<dt><i>LC_CTYPE</i><dd>
This variable will determine the
locale for the interpretation of sequences of bytes of text data as
characters (for example, single-
versus multi-byte characters in arguments),
the behaviour of character classes within
the pattern matching notation used for the
<b>-n</b>
option,
and the behaviour of character classes within
regular expressions
used in the extended regular expression defined for the
<b>yesexpr</b>
locale keyword in the LC_MESSAGES category.

<dt><i>LC_MESSAGES</i><dd>
Determine the locale for the processing of affirmative responses
that should be used to affect the format and contents of diagnostic
messages written to standard error.

<dt><i>NLSPATH</i><dd>
Determine the location of message catalogues
for the processing of
<i>LC_MESSAGES .
</i>
<dt><i>PATH</i><dd>Determine the location of the
<i>utility_name</i>
for the
<b>-exec</b>
and
<b>-ok</b>
primaries, as described in
the <b>XBD</b> specification, <a href="../xbd/envvar.html"><b>Environment Variables</b>&nbsp;</a> .

</dl>
</blockquote><h4><a name = "tag_001_014_746">&nbsp;</a>ASYNCHRONOUS EVENTS</h4><blockquote>
Default.
</blockquote><h4><a name = "tag_001_014_747">&nbsp;</a>STDOUT</h4><blockquote>
The
<b>-print</b>
primary will cause the current pathnames to be written to standard output.
The format will be:
<p><code>
<tt>"%s\n"</tt>, &lt;<i>path</i>&gt;
</code>
</blockquote><h4><a name = "tag_001_014_748">&nbsp;</a>STDERR</h4><blockquote>
The
<b>-ok</b>
primary
will write a prompt to standard error containing at least the
<i>utility_name</i>
to be invoked and the current pathname.
In the POSIX locale, the last
non-blank character in the prompt will be
"?".
The exact format used is unspecified.
<p>
Otherwise, the standard error will be used only for diagnostic messages.
</blockquote><h4><a name = "tag_001_014_749">&nbsp;</a>OUTPUT FILES</h4><blockquote>
None.
</blockquote><h4><a name = "tag_001_014_750">&nbsp;</a>EXTENDED DESCRIPTION</h4><blockquote>
None.
</blockquote><h4><a name = "tag_001_014_751">&nbsp;</a>EXIT STATUS</h4><blockquote>
The following exit values are returned:
<dl compact>

<dt>0<dd>All
<i>path</i>
operands were traversed successfully.

<dt>&gt;0<dd>An error occurred.

</dl>
</blockquote><h4><a name = "tag_001_014_752">&nbsp;</a>CONSEQUENCES OF ERRORS</h4><blockquote>
Default.
</blockquote><h4><a name = "tag_001_014_753">&nbsp;</a>APPLICATION USAGE</h4><blockquote>
When used in operands,
pattern matching notation,
semicolons, opening parentheses, and closing parentheses are
special to the shell and must be quoted (see
<a href="chap2.html#tag_001_002">
Quoting
</a>).
<p>
The bit that is traditionally used for sticky (historically 01000)
is still specified in the
<b>-perm</b>
primary using the octal number argument form.
Since this bit is not defined by this specification,
applications must not assume that it actually refers
to the traditional sticky bit.
<p>
The references to octal modes are marked EX
because, although they are obsolescent in the ISO/IEC 9945-2:1993 standard,
The Open Group is committed to maintaining them
for portable applications until further notice.
</blockquote><h4><a name = "tag_001_014_754">&nbsp;</a>EXAMPLES</h4><blockquote>
<ol>
<li>
The following commands are equivalent:
<pre>
<code>
find .
find . -print
</code>
</pre>
They both write out the entire directory hierarchy from the current directory.
<p>
<li>
The following command:
<pre>
<code>
find / \( -name tmp -o -name '*.xx' \) -atime +7 -exec rm {} \;
</code>
</pre>
removes all files named
<b>tmp</b>
or ending in
.xx
that have not been accessed for seven
or more 24-hour periods.
<p>
<li>
The following command:
<pre>
<code>
find . -perm -o+w,+s
</code>
</pre>
prints
(<b>-print</b>
is assumed) the names of all files in or below the
current directory, with all of the file permission bits
S_ISUID, S_ISGID and S_IWOTH set.
<p>
<li>
The following command:
<pre>
<code>
find . -name SCCS -prune -o -print
</code>
</pre>
recursively prints pathnames of all files in the current
directory and below, but skips directories named SCCS and
files in them.
<p>
<li>
The following command:
<pre>
<code>
find . -print -name SCCS -prune
</code>
</pre>
behaves as in the previous example, but prints the names of the
SCCS directories.
<br>
<p>
<li>
The following command is roughly equivalent to the
<b>-nt</b>
extension to
<i><a href="test.html">test</a></i>:
<pre>
<code>
if [ -n "$(find file1 -prune -newer file2)" ]; then
    printf %s\\n "file1 is newer than file2"
fi
</code>
</pre>
<p>
<li>
The descriptions of
<b>-atime</b>,
<b>-ctime</b>
and
<b>-mtime</b>
use the terminology
<i>n</i>
&quot;24-hour periods&quot;.
For example, a file accessed at
23:59 will be selected by:
<pre>
<code>
find . -atime -1 -print
</code>
</pre>
at 00:01 the next day (less than 24 hours later, not
more than one day ago); the midnight boundary between
days has no effect on the 24-hour calculation.
<p>
</ol>
</blockquote><h4><a name = "tag_001_014_755">&nbsp;</a>FUTURE DIRECTIONS</h4><blockquote>
The IEEE PASC 1003.2 Interpretations Committee has forwarded concerns about 
parts of this interface definition to the IEEE PASC Shell and Utilities Working Group
which is identifying the corrections.
A future revision of this specification will align with
IEEE Std. 1003.2b when finalised.
</blockquote><h4><a name = "tag_001_014_756">&nbsp;</a>SEE ALSO</h4><blockquote>
<i><a href="chmod.html">chmod</a></i>,
<i><a href="pax.html">pax</a></i>,
<i><a href="sh.html">sh</a></i>,
<i><a href="test.html">test</a></i>,
the <b>XSH</b> specification description of
<i><a href="../xsh/stat.html">stat()</a></i>.
</blockquote><hr size=2 noshade>
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