grep linux command

Find the lines that are matching for a given string from the specified file.


Syntax:


grep <option> "pattern" /path/of /file/to/be/searched


Example:


grep root /etc/passwd – The command searches for the pattern root in the file /etc/passwd and print the lines that matches the pattern.

grep -c /bin/tcsh /etc/passwd - List the number of users who use tcsh

grep -l '^#include' /usr/include/* - List header files that have at least one #include directive

Options:




-c, --count
              It prints a count of matching  lines for  each  input  file.



 -n, --line-number
              Print each line of output with the line number within its input
              file.



-o, --only-matching
              Show only the part of a matching line that matches the pattern.



-R, -r, --recursive
              Read all files under each directory, recursively; this is equiv-
              alent to the -d recurse option.