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TEST(1) NetBSD General Commands Manual TEST(1)
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by Kimmo Suominen.
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test, [ -- condition evaluation utility
[ expression ]
The test utility evaluates expression and, if it evaluates to true,
returns a zero (true) exit status; otherwise it returns 1 (false). If
expression is not given, 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.
-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 exists and 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.
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. This operator
is retained for compatibility with previous versions of
this program. Do not rely on its existence; use -h
-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 ASCII value
of their characters.
s1 > s2 True if string s1 comes after s2 based on the ASCII 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
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 inte-
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:
! 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 is true.
( expression )
True if expression is true.
The -a operator has higher precedence than the -o operator.
Note that all file tests with the exception of -h and -L follow symbolic
links and thus evaluate the test for the file pointed at.
The test utility exits with one of the following values:
0 expression evaluated to true.
1 expression evaluated to false or was missing.
>1 An error occurred.
The test utility implements a superset of the IEEE Std 1003.2
A test utility appeared in Version 7 AT&T UNIX.
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
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.
This means that test should not be used with more than 4 operands (where
the terminating ] in the case of the [ command does not count as an oper-
and,) and that the obsolete -a and -o options should not be used.
Instead invoke test multiple times connected by the ``&&'' and ``||''
operators from sh(1). When those operators are not used, there is no
need for the parentheses as grouping symbols, so those should also be
avoided. Using sh(1)'s ! command instead of the equivalent operator from
test can also protect the script from future test enhancements.
Most expressions with 3 or less operands will evaluate as expected,
though be aware that with 3 operands, if the second is a known binary
operator, that is always evaluated, regardless of what the other operands
might suggest had been intended. If, and only if, the middle operand is
not a defined binary operator is the first operand examined to see if it
is ! in which case the remaining operands are evaluated as a two operand
test, and the result inverted. The only other defined three operand case
is the meaningless degenerate case where parentheses (1st and 3rd oper-
ands) surround a one operand expression.
With 4 operands there are just two defined cases, the first where the
first operand is ! in which case the result of the three operand test on
the remaining operands is inverted, and the second is similar to the 3
operand case, the degenerate case of parentheses surrounding an (in this
case) 2 operand test expression.
NetBSD 10.99 October 17, 2017 NetBSD 10.99