test, [ —
condition evaluation utility
The test utility evaluates the
expression and, if it evaluates to true, returns a
zero (true) exit status; otherwise it returns 1 (false). If no
expression is given, test also
returns 1 (false). The form [ is an alias for
test.
All operators and flags are separate arguments to the
test utility. Symbolic links are followed for all
primaries except -h and
-L.
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 group matches the
effective group ID of this process.
-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.
-k
file- True if file exists and its sticky bit is set.
-L
file- True if file exists and is a symbolic link. This
operator is for compatibility purposes. Do not rely on its existence; use
-h instead.
-n
string- True if the length of string is nonzero.
-O
file- True if file exists and its owner matches the
effective user ID of this process.
-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 is a socket.
-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 (default 1) 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.
- 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.
- 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 ASCII value of their
characters.
- s1
>
s2
- True if string s1 comes after
s2 based on the ASCII value of their
characters.
- s1
- True if s1 is not the null string.
- 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.
These primaries can be combined with the following operators. The
-a operator has higher precedence than the
-o operator.
!
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 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.
The test grammar is inherently ambiguous.
In order to assure a degree of consistency, the cases described in
IEEE Std 1003.2 (“POSIX.2”) section
D11.2/4.62.4 are evaluated consistently according to the rules specified in
the standards document. All other cases are subject to the ambiguity in the
command semantics.
The test utility is compliant with the
IEEE Std 1003.1-2008 (“POSIX.1”)
specification.
The primaries -G,
-k, -O,
-nt, -ot,
-ef, <, and
> are extensions to that specification.
The operators -a,
-o, and () are marked by
IEEE Std 1003.1-2008 (“POSIX.1”) as
part of X/Open System Interfaces and obsolete.
test also exists as a built-in to
ksh(1), though with a different syntax.
A test utility appeared in
Version 7 AT&T UNIX.