grep regex with hyphens and white spaces

Question

I am trying to fetch a line with the following information -a string1 -b file1.txt -c string3 using grep.

I tried grep -v grep | grep '[b][:space:] *.txt *[c]' grep -v grep | grep '[b] *.txt *[c]'

string1, string3 and file1 are variables. So I am looking for solutions using wild characters.

But there is nothing returned. Any help will be appreciated.

Just use: grep -F -- '-a string1 -b file1.txt -c string3' file — anubhava
– anubhava, Commented Nov 12, 2019 at 19:51
Sorry, I wasn't clear in the question. string1, string3 and file1 are variables. So I am looking for solutions using wild characters. — sa_penguin
– sa_penguin, Commented Nov 12, 2019 at 19:57
You have a couple of misunderstandings of regex syntax: in regex, "*" doesn't mean "any string", it means "zero or more of whatever's right before this". To get "any string", you need "zero or more of any character", which is ".*". Also, to use a named character class, you need square brackets inside a square bracket expression (i.e. two sets of square brackets): "[[:space:]]" — Gordon Davisson
– Gordon Davisson, Commented Nov 12, 2019 at 23:16

anubhava · Accepted Answer · 2019-11-12 19:59:30Z

You may use this grep:

grep -- '-a [^[:blank:]]* -b [^[:blank:]]*.txt -c [^[:blank:]]*' *.txt

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