mirror of https://github.com/CrimsonTome/tldr.git
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>pull/6/head
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> Evaluate expressions and manipulate strings.
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> Evaluate expressions and manipulate strings.
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> More information: <https://www.gnu.org/software/coreutils/expr>.
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> More information: <https://www.gnu.org/software/coreutils/expr>.
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- Get string length:
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- Get the length of a specific string:
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`expr length {{string}}`
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`expr length "{{string}}"`
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- Evaluate logical or math expression with an operator ('+', '-', '*', '&', '|', etc.). Special symbols should be escaped:
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- Get the substring of a string with a specific length:
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`expr {{first_argument}} {{operator}} {{second_argument}}`
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`expr substr "{{string}}" {{from}} {{length}}`
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- Get position of the first character in 'string' that matches 'substring':
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- Match a specific substring against an anchored pattern:
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`echo $(expr index {{string}} {{substring}})`
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`expr match "{{string}}" '{{pattern}}'`
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- Extract part of the string:
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- Get the first char position from a specific set in a string:
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`echo $(expr substr {{string}} {{position_to_start}} {{number_of_characters}}`
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`expr index "{{string}}" "{{chars}}"`
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- Extract part of the string which matches a regular expression:
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- Calculate a specific mathematic expression:
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`echo $(expr {{string}} : '\({{regular_expression}}\)')`
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`expr {{expression1}} {{+|-|*|/|%}} {{expression2}}`
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- Get the first expression if its value is non-zero and not null otherwise get the second one:
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`expr {{expression1}} \| {{expression2}}`
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- Get the first expression if both expressions are non-zero and not null otherwise get zero:
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`expr {{expression1}} \& {{expression2}}`
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