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What is the use of ? in grep command.. And practical use

Fresh3 days ago
Mar 15, 202622158 views
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Problem

I tried to find the actual practical use of ? i.e. for e.g. "egrep a? filename" but was not able to find any.. It returns all results.. So, Please help me out wherein i could know the actual use of egrep ? command.. If i use 'a?', it returns all result i.e. strings or lines. which has 0 a's, 1 a's,…

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Fix for: What is the use of ? in grep command.. And practical use

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Say you wanted to match numeric assignment expressions like this in a script: where some numbers are negative and have a minus sign: You could use this: The question mark makes the minus optional. (I don't think plain grep supports or , hence ).

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