test command in UNIX

test EXPRESSION
test
[ EXPRESSION ]
[ ]
[ OPTION

Introduction

test command checks file types and compare values.

Options

Here are some of the options that you will use the most for string and variables:

• ( EXPRESSION ): EXPRESSION is true
• ! EXPRESSION: EXPRESSION is false
• -n STRING: the length of STRING is nonzero
• -z STRING: the length of STRING is zero
• STR1 = STR2: the strings are equal
• STR1 != STR2: the strings are not equal
• INT1 -eq INT2: INT1 is equal to INT2
• INT1 -ge INT2: INT1 is greater than or equal to INT2
• INT1 -gt INT2: INT1 is greater than INT2
• INT1 -le INT2: INT1 is less than or equal to INT2
• INT1 -lt INT2: INT1 is less than INT2
• INT1 -ne INT2: INT1 is not equal to INT2

Here are some of the options that you will use the most for files:

• -e FILE: file exists
• -d FILE: file exists and is a directory
• -f FILE: file exists and is a regular file
• FILE1 -nt FILE2: FILE1 is newer than FILE2 (by modification date)
• FILE1 -ot FILE2: FILE1 is older than FILE2
• -s FILE: file exists and has a size greater than zero
• -r FILE: file exists and read permission is granted
• -w FILE: file exists and write permission is granted
• -x FILE: file exists and execute (or search) permission is granted

Examples

Variable comparison

$? stores integer value returned by the last executed command. The semicolon ; separates multiple commands written on the same line.

test command for variables values comparison works in this way:

#
x="a"; y="a"; test "$x" = "$y"
echo $?
0 # no problems occurred

x="a"; y="b"; test "$x" = "$y";
echo $?
1 # a problem occurred: $x and $y are not equal

Quotes

Manual reference:

• man7.org - test