TEST(1) User Commands TEST(1)


NAME


test - evaluate condition(s)

SYNOPSIS


/usr/bin/test [condition]


[ [condition] ]


sh
test [condition]


[ [condition] ]


csh
test [condition]


[ [condition] ]


ksh
test [condition]


[ [condition] ]


ksh93
test [condition]


[ [condition] ]


DESCRIPTION


The test utility evaluates the condition and indicates the result of the
evaluation by its exit status. An exit status of zero indicates that the
condition evaluated as true and an exit status of 1 indicates that the
condition evaluated as false.


In the first form of the utility shown using the SYNOPSIS:

test [condition]


the square brackets denote that condition is an optional operand and are
not to be entered on the command line.


In the second form of the utility shown using the SYNOPSIS:

[ [ condition ] ]


the first open square bracket, [, is the required utility name.
condition is optional, as denoted by the inner pair of square brackets.
The final close square bracket, ], is a required operand.


See largefile(5) for the description of the behavior of test when
encountering files greater than or equal to 2 Gbyte (2^31 bytes).


The test and [ utilities evaluate the condition condition and, if its
value is true, set exit status to 0. Otherwise, a non-zero (false) exit
status is set. test and [ also set a non-zero exit status if there are no
arguments. When permissions are tested, the effective user ID of the
process is used.


All operators, flags, and brackets (brackets used as shown in the last
SYNOPSIS line) must be separate arguments to these commands. Normally
these arguments are separated by spaces.

OPERANDS


The primaries listed below with two elements of the form:

-primary_operator primary_operand


are known as unary primaries. The primaries with three elements in either
of the two forms:

primary_operand -primary_operator primary_operand
primary_operand primary_operator primary_operand


are known as binary primaries.


If any file operands except for -h and -L primaries refer to symbolic
links, the symbolic link is expanded and the test is performed on the
resulting file.


If you test a file you own (the -r -w or -x tests), but the permission
tested does not have the owner bit set, a non-zero (false) exit status is
returned even though the file can have the group or other bit set for
that permission.


The = and != primaries have a higher precedence than the unary primaries.
The = and != primaries always expect arguments; therefore, = and !=
cannot be used as an argument to the unary primaries.


The following primaries can be used to construct condition:

-a file
True if file exists. (Not available in sh.)


-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. (Not available in sh.)


-f file
True if file exists and is a regular file.
Alternatively, if /usr/bin/sh users specify
/usr/ucb before /usr/bin in their PATH
environment variable, then test returns true
if file exists and is (not-a-directory). The
csh test and [ built-ins always use this
alternative behavior.


-g file
True if file exists and its set group ID flag
is set.


-G file
True if file exists and its group matches the
effective group ID of this process. (Not
available in sh.)


-h file
True if file exists and is a symbolic link.


-k file
True if file exists and has its sticky bit
set.


-L file
True if file exists and is a symbolic link.


-n string
True if the length of string is non-zero.


-o option
True if option named option is on. This
option is not available in csh or sh.


-O file
True if file exists and is owned by the
effective user ID of this process. This
option is not available in sh.


-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.


-S file
True if file exists and is a socket. This
option is not available in sh.


-t [file_descriptor]
True if the file whose file descriptor number
is file_descriptor is open and is associated
with a terminal. If file_descriptor is not
specified, 1 is used as a default value.


-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 string is zero.


file1 -nt file2
True if file1 exists and is newer than file2.
This option is not available in sh.


file1 -ot file2
True if file1 exists and is older than file2.
This option is not available in sh.


file1 -ef file2
True if file1 and file2 exist and refer to
the same file. This option is not available
in sh.


string
True if the string string is not the null
string.


string1 = string2
True if the strings string1 and string2 are
identical.


string1 != string2
True if the strings string1 and string2 are
not identical.


n1 -eq n2
True if the numbers n1 and n2 are
algebraically equal. A number may be integer,
floating point or floating-point constant
(such as [+/-]Inf, [+/-]NaN) in any format
specified by C99/XPG6/SUS.


n1 -ne n2
True if the numbers n1 and n2 are not
algebraically equal. A number may be integer,
floating point or floating-point constant
(such as [+/-]Inf, [+/-]NaN) in any format
specified by C99/XPG6/SUS.


n1 -gt n2
True if the number n1 is algebraically
greater than the number n2. A number may be
integer, floating point or floating-point
constant (such as [+/-]Inf, [+/-]NaN) in any
format specified by C99/XPG6/SUS.


n1 -ge n2
True if the number n1 is algebraically
greater than or equal to the number n2. A
number may be integer, floating point or
floating-point constant (such as [+/-]Inf,
[+/-]NaN) in any format specified by
C99/XPG6/SUS.


n1 -lt n2
True if the number n1 is algebraically less
than the number n2. A number may be integer,
floating point or floating-point constant
(such as [+/-]Inf, [+/-]NaN) in any format
specified by C99/XPG6/SUS.


n1 -le n2
True if the number n1 is algebraically less
than or equal to the number n2. A number may
be integer, floating point or floating-point
constant (such as [+/-]Inf, [+/-]NaN) in any
format specified by C99/XPG6/SUS.


condition1 -a condition2
True if both condition1 and condition2 are
true. The -a binary primary is left
associative and has higher precedence than
the -o binary primary.


condition1 -o condition2
True if either condition1 or condition2 is
true. The -o binary primary is left
associative.


These primaries can be combined with the following operators:

! condition
True if condition is false.


( condition )
True if condition is true. The parentheses ( ) can be
used to alter the normal precedence and associativity.
The parentheses are meaningful to the shell and,
therefore, must be quoted.


The algorithm for determining the precedence of the operators and the
return value that is generated is based on the number of arguments
presented to test. (However, when using the [...] form, the right-bracket
final argument is not counted in this algorithm.)


In the following list, $1, $2, $3 and $4 represent the arguments
presented to test as a condition, condition1, or condition2.

0 arguments:
Exit false (1).


1 argument:
Exit true (0) if $1 is not null. Otherwise, exit false.


2 arguments:

o If $1 is !, exit true if $2 is null, false if
$2 is not null.

o If $1 is a unary primary, exit true if the
unary test is true, false if the unary test is
false.

o Otherwise, produce unspecified results.


3 arguments:

o If $2 is a binary primary, perform the binary
test of $1 and $3.

o If $1 is !, negate the two-argument test of $2
and $3.

o Otherwise, produce unspecified results.


4 arguments:

o If $1 is !, negate the three-argument test of
$2, $3, and $4.

o Otherwise, the results are unspecified.


USAGE


Scripts should be careful when dealing with user-supplied input that
could be confused with primaries and operators. Unless the application
writer knows all the cases that produce input to the script, invocations
like test "$1" -a "$2" should be written as test "$1" && test "$2" to
avoid problems if a user supplied values such as $1 set to ! and $2 set
to the null string. That is, in cases where maximal portability is of
concern, replace test expr1 -a expr2 with test expr1 && test expr2, and
replace test expr1 -o expr2 with test expr1 || test expr2. But notice
that, in test, -a has higher precedence than -o, while && and || have
equal precedence in the shell.


Parentheses or braces can be used in the shell command language to effect
grouping.


Parentheses must be escaped when using sh. For example:

test \( expr1 -a expr2 \) -o expr3


This command is not always portable outside XSI-conformant systems. The
following form can be used instead:

( test expr1 && test expr2 ) || test expr3


The two commands:

test "$1"
test ! "$1"


could not be used reliably on some historical systems. Unexpected results
would occur if such a string condition were used and $1 expanded to !, (,
or a known unary primary. Better constructs are, respectively,

test -n "$1"
test -z "$1"


Historical systems have also been unreliable given the common construct:

test "$response" = "expected string"


One of the following is a more reliable form:

test "X$response" = "Xexpected string"
test "expected string" = "$response"


The second form assumes that expected string could not be confused with
any unary primary. If expected string starts with -, (, ! or even =, the
first form should be used instead. Using the preceding rules without the
marked extensions, any of the three comparison forms is reliable, given
any input. (However, observe that the strings are quoted in all cases.)


Because the string comparison binary primaries, = and !=, have a higher
precedence than any unary primary in the >4 argument case, unexpected
results can occur if arguments are not properly prepared. For example, in

test -d $1 -o -d $2


If $1 evaluates to a possible directory name of =, the first three
arguments are considered a string comparison, which causes a syntax error
when the second -d is encountered. is encountered. One of the following
forms prevents this; the second is preferred:

test \( -d "$1" \) -o \( -d "$2" \)
test -d "$1" || test -d "$2"


Also in the >4 argument case:

test "$1" = "bat" -a "$2" = "ball"


Syntax errors occur if $1 evaluates to ( or !. One of the following forms
prevents this; the third is preferred:

test "X$1" = "Xbat" -a "X$2" = "Xball"
test "$1" = "bat" && test "$2" = "ball"
test "X$1" = "Xbat" && test "X$2" = "Xball"


EXAMPLES


In the if command examples, three conditions are tested, and if all three
evaluate as true or successful, then their validities are written to the
screen. The three tests are:

o if a variable set to 1 is greater than 0,

o if a variable set to 2 is equal to 2, and

o if the word root is included in the text file /etc/passwd.

/usr/bin/test

Example 1: Using /usr/bin/test




Perform a mkdir if a directory does not exist:


test ! -d tempdir && mkdir tempdir


Wait for a file to become non-readable:


while test -r thefile
do
sleep 30
done
echo'"thefile" is no longer readable'


Perform a command if the argument is one of three strings (two
variations), using the open bracket version [ of the test command:


if [ "$1" = "pear" ] || [ "$1" = "grape" ] || [ "$1" = "apple" ]
then
command
fi
case "$1" in
pear|grape|apple) command;;
esac


Example 2: Using /usr/bin/test for the -e option




If one really wants to use the -e option in sh, use /usr/bin/test, as in
the following:


if [ ! -h $PKG_INSTALL_ROOT$rLink ] && /usr/bin/test -e
$PKG_INSTALL_ROOT/usr/bin/$rFile ; then
ln -s $rFile $PKG_INSTALL_ROOT$rLink
fi


The test built-in
The two forms of the test built-in follow the Bourne shell's if example.

Example 3: Using the sh built-in



ZERO=0 ONE=1 TWO=2 ROOT=root

if [ $ONE -gt $ZERO ]

[ $TWO -eq 2 ]

grep $ROOT /etc/passwd >&1 > /dev/null # discard output

then

echo "$ONE is greater than 0, $TWO equals 2, and $ROOT is" \
"a user-name in the password file"

else

echo "At least one of the three test conditions is false"
fi


Example 4: Using the test built-in




Examples of the test built-in:


test `grep $ROOT /etc/passwd >&1 /dev/null` # discard output

echo $? # test for success
[ `grep nosuchname /etc/passwd >&1 /dev/null` ]

echo $? # test for failure


csh

Example 5: Using the csh built-in



@ ZERO = 0; @ ONE = 1; @ TWO = 2; set ROOT = root
grep $ROOT /etc/passwd >&1 /dev/null # discard output
# $status must be tested for immediately following grep
if ( "$status" == "0" && $ONE > $ZERO && $TWO == 2 ) then
echo "$ONE is greater than 0, $TWO equals 2, and $ROOT is" \
"a user-name in the password file"
endif


ksh

Example 6: Using the ksh/ksh93 built-in



ZERO=0 ONE=1 TWO=$((ONE+ONE)) ROOT=root
if ((ONE > ZERO)) # arithmetical comparison
[[ $TWO = 2 ]] # string comparison
[ `grep $ROOT /etc/passwd >&1 /dev/null` ] # discard output
then
echo "$ONE is greater than 0, $TWO equals 2, and $ROOT is" \
"a user-name in the password file"

else
echo "At least one of the three test conditions is false"
fi


ENVIRONMENT VARIABLES


See environ(5) for descriptions of the following environment variables
that affect the execution of test: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES,
and NLSPATH.

EXIT STATUS


The following exit values are returned:

0
condition evaluated to true.


1
condition evaluated to false or condition was missing.


>1
An error occurred.


ATTRIBUTES


See attributes(5) for descriptions of the following attributes:

/usr/bin/test, csh, ksh, sh

+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|Interface Stability | Committed |
+--------------------+-------------------+
|Standard | See standards(5). |
+--------------------+-------------------+

ksh93

+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Uncommitted |
+--------------------+-----------------+

SEE ALSO


csh(1), ksh(1), ksh93(1), sh(1), test(1B), attributes(5), environ(5),
largefile(5), standards(5)

NOTES


The not-a-directory alternative to the -f option is a transition aid for
BSD applications and may not be supported in future releases.

XPG4 sh, ksh, ksh93
Use arithmetic expressions such as

$(( x > 3.1 )) #


instead of

$ /usr/bin/test "$x" -gt 3.1 # )


when comparing two floating-point variables or a constant and a floating-
point variable to prevent rounding errors (caused by the base16 to base10
transformation) to affect the result. Additionally the built-in
arithmetic support in XPG4 sh, ksh and ksh93 is significantly faster
because it does not require the explicit transformation to strings for
each comparison.


August 11, 2009 TEST(1)