Test

Syntax#

• test
• test [!] [ -n | -z ] string
• test [!] { -b | -c | -d | -e | -f | -g | -h | -L | -p | -r | -S | -s | -u | -w | -x } file
• test [!] -t fd
• test [!] string { = | != } string
• test [!] integer { -eq | -ne | -gt | -ge | -lt | -le } integer
• [ ]
• [ [!] [ -n | -z ] string ]
• [ [!] { -b | -c | -d | -e | -f | -g | -h | -L | -p | -r | -S | -s | -u | -w | -x } file ]
• [ [!] -t fd ]
• [ [!] string { = | != } string ]
• [ [!] integer { -eq | -ne | -gt | -ge | -lt | -le } integer ]

Remarks#

If test(1) is run without any arguments it returns false.

Reference

• Standard test(1)
• The FreeBSD test(1) man-page
• The NetBSD test(1) man-page
• The OpenBSD test(1) man-page
• The Illumos test(1) man-page
• The GNU Coreutils online manual section on test(1)

Multiple Expressions

Though it is an obsoleted part of the XSI standard, many implementations still support multiple expressions with Boolean operators and parenthesis.

The (obsolete) operators are listed below with decreasing precedence.

( expression )
expression -a expression
expression -o expression

Using these (obsolete) operators, a complex shell expression:

if [ "$a" -gt 0 ] && { [ "$b" -ne 2 ] || [ "$b" -e 0 ]; }
then ...
fi

Could be written with one invocation of test(1):

if [ "$a" -gt 0 -a '(' "$b" -ne 2 -o "$c" -ne 0 ')' ]
then ...
fi