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tldr/pages/common/expr.md
Emily Grace Seville 6ea92d50ed
expr: refresh page (#7999) 
* Refresh page:
- better grammar in descriptions
- more examples
- reorder examples

* Fix the last example

* Some rewordings

Co-authored-by: Muhammad Falak R Wani <falakreyaz@gmail.com>

* Rewording again

* Fix errors

* Change placeholders:

- use an actual value in some placeholders
- use generic placeholders instead of some actual values

* Add note about supported operators

* Update pages/common/expr.md

Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>

* Fix quoting and simplify descriptions

* Fix `index` description

* Apply suggestions from code review

---------

Co-authored-by: Muhammad Falak R Wani <falakreyaz@gmail.com>
Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>
2023-02-21 15:27:06 +05:30

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expr

Evaluate expressions and manipulate strings. More information: https://www.gnu.org/software/coreutils/expr.

  • Get the length of a specific string:

expr length "{{string}}"

  • Get the substring of a string with a specific length:

expr substr "{{string}}" {{from}} {{length}}

  • Match a specific substring against an anchored pattern:

expr match "{{string}}" '{{pattern}}'

  • Get the first char position from a specific set in a string:

expr index "{{string}}" "{{chars}}"

  • Calculate a specific mathematic expression:

expr {{expression1}} {{+|-|*|/|%}} {{expression2}}

  • Get the first expression if its value is non-zero and not null otherwise get the second one:

expr {{expression1}} \| {{expression2}}

  • Get the first expression if both expressions are non-zero and not null otherwise get zero:

expr {{expression1}} \& {{expression2}}