Date : 05-07-2021
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 |
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 |