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Man Pages


Manual Reference Pages  -  TEST (1)

NAME

test, [ - condition evaluation utility

CONTENTS

Synopsis
Description
Grammar Ambiguity
Exit Status
Examples
Compatibility
See Also
Standards
Bugs

SYNOPSIS

test expression [ expression ]

DESCRIPTION

The test utility evaluates the expression and, if it evaluates to true, returns a zero (true) exit status; otherwise it returns 1 (false). If there is no expression, test also returns 1 (false).

All operators and flags are separate arguments to the test utility.

The following primaries are used to construct expression:
-b file
  True if file exists and is a block special file.
-c file
  True if file exists and is a character special file.
-d file
  True if file exists and is a directory.
-e file
  True if file exists (regardless of type).
-f file
  True if file exists and is a regular file.
-g file
  True if file exists and its set group ID flag is set.
-h file
  True if file exists and is a symbolic link. This operator is retained for compatibility with previous versions of this program. Do not rely on its existence; use -L instead.
-k file
  True if file exists and its sticky bit is set.
-n string
  True if the length of string is nonzero.
-p file
  True if file is a named pipe (FIFO).
-r file
  True if file exists and is readable.
-s file
  True if file exists and has a size greater than zero.
-t file_descriptor
  True if the file whose file descriptor number is file_descriptor is open and is associated with a terminal.
-u file
  True if file exists and its set user ID flag is set.
-w file
  True if file exists and is writable. True indicates only that the write flag is on. The file is not writable on a read-only file system even if this test indicates true.
-x file
  True if file exists and is executable. True indicates only that the execute flag is on. If file is a directory, true indicates that file can be searched.
-z string
  True if the length of string is zero.
-L file
  True if file exists and is a symbolic link.
-O file
  True if file exists and its owner matches the effective user id of this process.
-G file
  True if file exists and its group matches the effective group id of this process.
-S file
  True if file exists and is a socket.
file1-nt file2
  True if file1 exists and is newer than file2.
file1-ot file2
  True if file1 exists and is older than file2.
file1-ef file2
  True if file1 and file2 exist and refer to the same file.
string
  True if string is not the null string.
s1 = s2
  True if the strings s1 and s2 are identical.
s1 != s2
  True if the strings s1 and s2 are not identical.
s1 < s2
  True if string s1 comes before s2 based on the binary value of their characters.
s1 > s2
  True if string s1 comes after s2 based on the binary value of their characters.
n1-eq n2
  True if the integers n1 and n2 are algebraically equal.
n1-ne n2
  True if the integers n1 and n2 are not algebraically equal.
n1-gt n2
  True if the integer n1 is algebraically greater than the integer n2.
n1-ge n2
  True if the integer n1 is algebraically greater than or equal to the integer n2.
n1-lt n2
  True if the integer n1 is algebraically less than the integer n2.
n1-le n2
  True if the integer n1 is algebraically less than or equal to the integer n2.

If file is a symbolic link, test will fully dereference it and then evaluate the expression against the file referenced, except for the -h and -L primaries.

These primaries can be combined with the following operators:
! expression
  True if expression is false.
expression1-a expression2
  True if both expression1 and expression2 are true.
expression1-o expression2
  True if either expression1 or expression2 are true.
( expression )
  True if expression is true.

The -a operator has higher precedence than the -o operator.

Some shells may provide a builtin test command which is similar or identical to this utility. Consult the builtin(1) manual page.

GRAMMAR AMBIGUITY

The test grammar is inherently ambiguous. In order to assure a degree of consistency, the cases described in the -p1003.2, section D11.2/4.62.4, standard are evaluated consistently according to the rules specified in the standards document. All other cases are subject to the ambiguity in the command semantics.

In particular, only expressions containing -a , -o , ( or ) can be ambiguous.

EXIT STATUS

The test utility exits with one of the following values:
0 expression evaluated to true.
1 expression evaluated to false or expression was missing.
>1 An error occurred.

EXAMPLES

Implement test FILE1 -nt FILE2 using only POSIX functionality:

    test -n $(find -L -- FILE1 -prune -newer FILE2 2>/dev/null)

This can be modified using non-standard find(1) primaries like -newerca to compare other timestamps.

COMPATIBILITY

For compatibility with some other implementations, the = primary can be substituted with == with the same meaning.

SEE ALSO

builtin(1), expr(1), find(1), sh(1), stat(1), symlink(7)

STANDARDS

The test utility implements a superset of the -p1003.2 specification. The primaries <, ==, >, -ef , -nt , -ot , -G , and -O are extensions.

BUGS

Both sides are always evaluated in -a and -o . For instance, the writable status of file will be tested by the following command even though the former expression indicated false, which results in a gratuitous access to the file system:

    [ -z abc -a -w file ]

To avoid this, write

    [ -z abc ] && [ -w file ]

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