$cat example.txt A for Apple. B for Baby. C for Cat. D for Donkey. $grep A example.txt A for Apple. $grep -x A example.txt $grep -x A for Apple. example.txt grep: for: No such file or directory grep: Apple.: No such file or directory $grep -x "A for Apple." example.txt A for Apple. $grep -x "A for Apple" example.txt $
grep -x option Select only those matches that exactly match the whole line. (-x is specified by POSIX.) source : debian grep manual.
case 'x': match_lines = 1; break; source : debian GNU grep.
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