mirror of https://github.com/CrimsonTome/tldr.git
24 lines
646 B
Markdown
24 lines
646 B
Markdown
|
# expr
|
||
|
|
|
||
|
|
> Evaluate expressions and manipulate strings.
|
||
|
|
|
||
|
|
- Get string length:
|
||
|
|
|
||
|
|
`expr length {{string}}`
|
||
|
|
|
||
|
- Evaluate logical or math expression with an operator ('+', '-', '*', '&', '|', etc.). Special symbols should be escaped:
|
||
|
|
|
||
|
|
`expr {{first_argument}} {{operator}} {{second_argument}}`
|
||
|
|
|
||
|
|
- Get position of the first character in 'string' that matches 'substring':
|
||
|
|
|
||
|
|
`echo $(expr index {{string}} {{substring}})`
|
||
|
|
|
||
|
|
- Extract part of the string:
|
||
|
|
|
||
|
|
`echo $(expr substr {{string}} {{position_to_start}} {{number_of_characters}}`
|
||
|
|
|
||
|
|
- Extract part of the string which matches a regular expression:
|
||
|
|
|
||
|
|
`echo $(expr {{string}} : '\({{regular_expression}}\)')`
|