| Mathematical Operator in Shell Script | Meaning | Normal Arithmetical/ Mathematical Statements | But in Shell |
| | | | For test statement with if command | For [ expr ] statement with if command |
| -eq | is equal to | 5 == 6 | if test 5 -eq 6 | if [ 5 -eq 6 ] |
| -ne | is not equal to | 5 != 6 | if test 5 -ne 6 | if [ 5 -ne 6 ] |
| -lt | is less than | 5 < 6 | if test 5 -lt 6 | if [ 5 -lt 6 ] |
| -le | is less than or equal to | 5 <= 6 | if test 5 -le 6 | if [ 5 -le 6 ] |
| -gt | is greater than | 5 > 6 | if test 5 -gt 6 | if [ 5 -gt 6 ] |
| -ge | is greater than or equal to | 5 >= 6 | if test 5 -ge 6 | if [ 5 -ge 6 ] |
NOTE: == is equal, != is not equal.
For string Comparisons use
| Operator | Meaning |
| string1 = string2 | string1 is equal to string2 |
| string1 != string2 | string1 is NOT equal to string2 |
| string1 | string1 is NOT NULL or not defined |
| -n string1 | string1 is NOT NULL and does exist |
| -z string1 | string1 is NULL and does exist |
Shell also test for file and directory types
| Test | Meaning |
| -s file | Non empty file |
| -f file | Is File exist or normal file and not a directory |
| -d dir | Is Directory exist and not a file |
| -w file | Is writeable file |
| -r file | Is read-only file |
| -x file | Is file is executable |
Logical Operators
Logical operators are used to combine two or more condition at a time
| Operator | Meaning |
| ! expression | Logical NOT |
| expression1 -a expression2 | Logical AND |
| expression1 -o expression2 | Logical OR |
