Linux and Unix test command

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About test
Syntax
Examples
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About test

Checks file types and compares values.

Syntax

test EXPRESSION
[ EXPRESSION ]

Description

test is used as part of the conditional execution of shell commands.

test exits with the status determined by EXPRESSION. Placing the EXPRESSION between square brackets ([ and ]) is the same as testing the EXPRESSION with test. To see the exit status at the command prompt, echo the value "$?" A value of 0 means the expression evaluated as true, and a value of 1 means the expression evaluated as false.

Expressions

Expressions take the following forms:

( EXPRESSION ) EXPRESSION is true
! EXPRESSION EXPRESSION is false
EXPRESSION1 -a EXPRESSION2 both EXPRESSION1 and EXPRESSION2 are true
EXPRESSION1 -o EXPRESSION2 either EXPRESSION1 or EXPRESSION2 is true
-n STRING the length of STRING is nonzero
STRING equivalent to -n STRING
-z STRING the length of STRING is zero
STRING1 = STRING2 the strings are equal
STRING1 != STRING2 the strings are not equal
INTEGER1 -eq INTEGER2 INTEGER1 is equal to INTEGER2
INTEGER1 -ge INTEGER2 INTEGER1 is greater than or equal to INTEGER2
INTEGER1 -gt INTEGER2 INTEGER1 is greater than INTEGER2
INTEGER1 -le INTEGER2 INTEGER1 is less than or equal to INTEGER2
INTEGER1 -lt INTEGER2 INTEGER1 is less than INTEGER2
INTEGER1 -ne INTEGER2 INTEGER1 is not equal to INTEGER2
FILE1 -ef FILE2 FILE1 and FILE2 have the same device and inode numbers
FILE1 -nt FILE2 FILE1 is newer (modification date) than FILE2
FILE1 -ot FILE2 FILE1 is older than FILE2
-b FILE FILE exists and is block special
-c FILE FILE exists and is character special
-d FILE FILE exists and is a directory
-e FILE FILE exists
-f FILE FILE exists and is a regular file
-g FILE FILE exists and is set-group-ID
-G FILE FILE exists and is owned by the effective group ID
-h FILE FILE exists and is a symbolic link (same as -L)
-k FILE FILE exists and has its sticky bit set
-L FILE FILE exists and is a symbolic link (same as -h)
-O FILE FILE exists and is owned by the effective user ID
-p FILE FILE exists and is a named pipe
-r FILE FILE exists and read permission is granted
-s FILE FILE exists and has a size greater than zero
-S FILE FILE exists and is a socket
-t FD file descriptor FD is opened on a terminal
-u FILE FILE exists and its set-user-ID bit is set
-w FILE FILE exists and write permission is granted
-x FILE FILE exists and execute (or search) permission is granted

Except for -h and -L, all FILE-related tests dereference symbolic links. Beware that parentheses need to be escaped (e.g., by backslashes) for shells. INTEGER may also be -l STRING, which evaluates to the length of STRING.

NOTE: your shell may have its own version of test, which usually supersedes the version described here. Please refer to your shell's documentation for details about the options it supports.

Examples

test 100 -gt 99 && echo "Yes, that's true." || echo "No, that's false."

This command will print the text "Yes, that's true." because 100 is greater than 99.

test 100 -lt 99 && echo "Yes." || echo "No."

This command will print the text "No." because 100 is not less than 99.

[ "awesome" = "awesome" ]; echo $?

This command will print "0" because the expression is true; the two strings are identical.

[ 5 -eq 6 ]; echo $?

This command will print "1" because the expression is false; 5 does not equal 6.