Variables can be assigned within arithmetic expressions.
| Notation | Description |
|---|---|
| parameter = value | Simple assignment. Assigns value to parameter. |
| paramater += value | parameter = parameter + value |
| parameter -= value | parameter = parameter - value |
| parameter *= value | parameter = parameter * value |
| parameter /= value | parameter = parameter / value |
| parameter %= value | parameter = parameter % value |
| parameter++ | Variable post-increment. |
| parameter = parameter + 1 | |
| parameter– | Variable post-decrement. |
| parameter = parameter - 1 | |
| ++parameter | Variable pre-increment. |
| parameter = parameter + 1 | |
| –parameter | Variable pre-decrement. |
| /parameter = paramter - 1 |
Post-increment/decrement and Pre-increment/decrement #
Post-increment and pre-increment (decrement) borrowed from C programming language. If pre the parameter is incremented/decremented before the parameter is returned. If post the operation is performed after the parameter is returned.
# post-incremented
[me@linuxbox ~]$ foo=1
[me@linuxbox ~]$ echo $((foo++))
1
[me@linuxbox ~]$ echo $foo
2
# pre-incremented
[me@linuxbox ~]$ foo=1
[me@linuxbox ~]$ echo $((++foo))
2
[me@linuxbox ~]$ echo $foo
2