mirror of https://github.com/CrimsonTome/tldr.git
25 lines
713 B
Markdown
25 lines
713 B
Markdown
# expr
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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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- Get string length:
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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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`expr {{first_argument}} {{operator}} {{second_argument}}`
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- Get position of the first character in 'string' that matches 'substring':
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`echo $(expr index {{string}} {{substring}})`
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- Extract part of the string:
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`echo $(expr substr {{string}} {{position_to_start}} {{number_of_characters}}`
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- Extract part of the string which matches a regular expression:
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`echo $(expr {{string}} : '\({{regular_expression}}\)')`
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