-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 would want to use them. You must specify `u', `g' or `o' if
you use a symbolic mode. See the EXAMPLES section for some illustrative examples.
-perm /mode
Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form.
You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some
illustrative examples. If no permission bits in mode are set, this test matches any file (the
idea here is to be consistent with the behaviour of -perm -000).
-perm +mode
Deprecated, old way of searching for files with any of the permission bits in mode set. You
should use -perm /mode instead. Trying to use the `+' syntax with symbolic modes will yield
surprising results. For example, `+u+x' is a valid symbolic mode (equivalent to +u,+x, i.e. 0111)
and will therefore not be evaluated as -perm +mode but instead as the exact mode specifier -perm
mode and so it matches files with exact permissions 0111 instead of files with any execute bit
set. If you found this paragraph confusing, you're not alone - just use -perm /mode. This form
of the -perm test is deprecated because the POSIX specification requires the interpretation of a
leading `+' as being part of a symbolic mode, and so we switched to using `/' instead.
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Before a command is executed, its input and output may be redirected using a special notation interpreted
by the shell. Redirection may also be used to open and close files for the current shell execution
environment. The following redirection operators may precede or appear anywhere within a simple command
or may follow a command. Redirections are processed in the order they appear, from left to right.
Redirecting Output
Redirection of output causes the file whose name results from the expansion of word to be opened for
writing on file descriptor n, or the standard output (file descriptor 1) if n is not specified. If the
file does not exist it is created; if it does exist it is truncated to zero size.
The general format for redirecting output is:
[n]>word
If the redirection operator is >, and the noclobber option to the set builtin has been enabled, the
redirection will fail if the file whose name results from the expansion of word exists and is a regular
file. If the redirection operator is >|, or the redirection operator is > and the noclobber option to
the set builtin command is not enabled, the redirection is attempted even if the file named by word
exists.
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