Bash Scripting

Date : 05-07-2021

Conditions

Note that [[ is actually a command/program that returns either 0 (true) or 1 (false) . Any program that obeys the same logic (like all base utils, such as grep(1) or ping(1) ) can be used as condition, see examples.

Condition	Description
[[ -z STRING ]]	Empty string
[[ -n STRING ]]	Not empty string
[[ STRING == STRING ]]	Equal
[[ STRING != STRING ]]	Not Equal
[[ NUM -eq NUM ]]	Equal
[[ NUM -ne NUM ]]	Not equal
[[ NUM -lt NUM ]]	Less than
[[ NUM -le NUM ]]	Less than or equal
[[ NUM -gt NUM ]]	Greater than
[[ NUM -ge NUM ]]	Greater than or equal
[[ STRING =~ STRING ]]	Regexp
(( NUM < NUM ))	Numeric conditions	>

Functions

Note that [[ is actually a command/program that returns either 0 (true) or 1 (false). Any program that obeys the same logic (like all base utils, such as grep(1) or ping(1)) can be used as condition.

Condition	Description
[[ -z STRING ]]	Empty string
[[ -n STRING ]]	Not empty string
[[ STRING == STRING ]]	Equal
[[ STRING != STRING ]]	Not Equal
[[ NUM -eq NUM ]]	Equal
[[ NUM -ne NUM ]]	Not equal
[[ NUM -lt NUM ]]	Less than
[[ NUM -le NUM ]]	Less than or equal
[[ NUM -gt NUM ]]	Greater than
[[ NUM -ge NUM ]]	Greater than or equal
[[ STRING =~ STRING ]]	Regexp
(( NUM < NUM ))	Numeric conditions