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Linux grep

The ‘grep’ command stands for “global regular expression print”. grep command filters the content of a file which makes our search easy.

grep with pipe

The ‘grep’ command is generally used with pipe (|).

Syntax:

Example:

Look at the above snapshot, grep command filters all the data containing ‘9’.

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grep without pipe

It can be used without pipe also.

Syntax:

Example:

Look at the above snapshot, grep command do the same work as earlier example but without pipe.

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grep options

• grep -vM: The ‘grep -v’ command displays lines not matching to the specified word.

Syntax:

grep -v

Example:

grep -v 9 marks.txt



Look at the above snapshot, command “grep -v 9 marks.txt” displays lines hwich don’t contain our search word ‘9’.

• grep -i: The ‘grep -i’ command filters output in a case-insensitive way.

Syntax:

grep -i

Example:

grep -i red exm.txt



Look at the above snapshot, command “grep -i red exm.txt” displays all lines containing ‘red’ whether in upper case or lower case.

• grep -A/ grep -B/ grep -C

  grep -A command is used to display the line after the result.

  grep -B command is used to display the line before the result.

  grep -C command is used to display the line after and line before the result.

  You can use (A1, A2, A3…..)(B1, B2, B3….)(C1, C2, C3….) to display any number of lines.

Syntax:

grep -A grep -B grep -C

Example:

grep -A1 yellow exm.txt grep -B1 yellow exm.txt grep -C1 yellow exm.txt



Look at the above snapshot, command “grep -A1 yellow exm.txt” displays searched line with next succeeding line, command “grep -B1 yellow exm.txt” displays searched line with one preceding line and command “grep -C1 yellow exm.txt” displays searched line with one preceding and succeeding line.