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109 lines
4.7 KiB
Text
109 lines
4.7 KiB
Text
\section test test - perform tests on files and text
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\subsection test-synopsis Synopsis
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<tt>test [EXPRESSION]</tt>
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\subsection test-description Description
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Tests the expression given and sets the exit status to 0 if true,
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and 1 if false. An expression is made up of one or more operators
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and their arguments.
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The following operators are available to examine files and directories:
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- <tt>-b FILE</tt> returns true if \c FILE is a block device.
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- <tt>-c FILE</tt> returns true if \c FILE is a character device.
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- <tt>-d FILE</tt> returns true if \c FILE is a directory.
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- <tt>-e FILE</tt> returns true if \c FILE exists.
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- <tt>-f FILE</tt> returns true if \c FILE is a regular file.
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- <tt>-g FILE</tt> returns true if \c FILE has the set-group-ID bit set.
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- <tt>-G FILE</tt> returns true if \c FILE exists and has the same group ID
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as the current user.
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- <tt>-L FILE</tt> returns true if \c FILE is a symbolic link.
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- <tt>-O FILE</tt> returns true if \c FILE exists and is owned by the current
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user.
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- <tt>-p FILE</tt> returns true if \c FILE is a named pipe.
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- <tt>-r FILE</tt> returns true if \c FILE is marked as readable.
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- <tt>-s FILE</tt> returns true if the size of \c FILE is greater than zero.
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- <tt>-S FILE</tt> returns true if \c FILE is a socket.
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- <tt>-t FD</tt> returns true if the file descriptor \c FD is a terminal (TTY).
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- <tt>-u FILE</tt> returns true if \c FILE has the set-user-ID bit set.
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- <tt>-w FILE</tt> returns true if \c FILE is marked as writable; note that this does not check if the filesystem is read-only.
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- <tt>-x FILE</tt> returns true if \c FILE is marked as executable.
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The following operators are available to compare and examine text strings:
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- <tt>STRING1 = STRING2</tt> returns true if the strings \c STRING1 and
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\c STRING2 are identical.
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- <tt>STRING1 != STRING2</tt> returns true if the strings \c STRING1 and
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\c STRING2 are not identical.
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- <tt>-n STRING</tt> returns true if the length of \c STRING is non-zero.
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- <tt>-z STRING</tt> returns true if the length of \c STRING is zero.
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The following operators are available to compare and examine numbers:
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- <tt>NUM1 -eq NUM2</tt> returns true if \c NUM1 and \c NUM2 are numerically equal.
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- <tt>NUM1 -ne NUM2</tt> returns true if \c NUM1 and \c NUM2 are not numerically equal.
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- <tt>NUM1 -gt NUM2</tt> returns true if \c NUM1 is greater than <tt>NUM2</tt>.
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- <tt>NUM1 -ge NUM2</tt> returns true if \c NUM1 is greater than or equal to <tt>NUM2</tt>.
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- <tt>NUM1 -lt NUM2</tt> returns true if \c NUM1 is less than <tt>NUM2</tt>.
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- <tt>NUM1 -le NUM2</tt> returns true if \c NUM1 is less than or equal to <tt>NUM2</tt>.
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Note that only integers are supported. For more complex mathematical
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operations, including fractions, the \c env program may be useful. Consult the
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documentation for your operating system.
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Expressions can be combined using the following operators:
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- <tt>COND1 -a COND2</tt> returns true if both \c COND1 and \c COND2 are true.
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- <tt>COND1 -o COND2</tt> returns true if either \c COND1 or \c COND2 are true.
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Expressions can be inverted using the \c ! operator:
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- <tt>! EXPRESSION</tt> returns true if \c EXPRESSION is false, and false if
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\c EXPRESSION is true.
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Expressions can be grouped using parentheses.
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- <tt>( EXPRESSION )</tt> returns the value of <tt>EXPRESSION</tt>.
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Note that parentheses will usually require escaping with <tt>\\(</tt> to avoid
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being interpreted as a command substitution.
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\subsection test-example Examples
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If the \c /tmp directory exists, copy the \c /etc/motd file to it:
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<pre>
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if test -d /tmp
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cp /etc/motd /tmp/motd
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end
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</pre>
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If the variable \c MANPATH is defined and not empty, print the contents.
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(If \c MANPATH is not defined, then it will expand to zero arguments, unless
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quoted.)
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<pre>
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if test -n "$MANPATH"
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echo $MANPATH
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end
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</pre>
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Parentheses and the \c -o and \c -a operators can be combined to produce
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more complicated expressions. In this example, success is printed if there is
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a \c /foo or \c /bar file as well as a \c /baz or \c /bat file.
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<pre>
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if test \\( -f /foo -o -f /bar \\) -a \\( -f /baz -o -f /bat \\)
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echo Success.
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end.
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</pre>
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\subsection test-standards Standards
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\c test implements a subset of the
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<a href="http://www.unix.com/man-page/POSIX/1/test/">IEEE Std 1003.1-2008
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(POSIX.1) standard</a>. The following exceptions apply:
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- The \c < and \c > operators for comparing strings are not implemented.
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- Because this test is a shell builtin and not a standalone utility, using
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the -c flag on a special file descriptors like standard input and output
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may not return the same result when invoked from within a pipe as one
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would expect when invoking the \c test utility in another shell.
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In cases such as this, one can use \c command \c test to explicitly
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use the system's standalone \c test rather than this \c builtin \c test.
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