Grep

FLOPPIX

The grep command searches the contents of a file for lines that contain a certain pattern.

Examples:

grep flin /etc/passwd
Display the lines from the file /etc/passwd that contain the string flin.

grep -v flin /etc/passwd
Display the lines from the file /etc/passwd that do not contain the string flin.

grep -n flin /etc/passwd
Display line numbers and the lines from the file /etc/passwd that contain the string flin.

grep ^f /etc/passwd
Display the lines from the file /etc/passwd that start with f.

grep h$ /etc/passwd
Display the lines from the file /etc/passwd that end with h.

Use the grep command to display the lines from the file /etc/passwd for users with the flin login shell.
Use the grep command to display the lines from the file /etc/hosts.deny that are NOT comment lines (the comment lines are the lines that start with #).
Use the grep command to display all lines from any file in /etc/init.d that start with echo.
Which files in /etc/init.d contain the string "dmesg"? ____________________
Which files in /etc/init.d contain the word tr? _________________________
Note: use the man command to lookup to option for grep that searches for the word "tr" instead of the string "tr".

What command will display all lines in /etc/init.d/userinitials that start with echo?

Answer: grep ^echo /etc/init.d/userinitials
What command will display all lines that contain echo in any file in the directory /etc/init.d?

Answer: grep echo /etc/init.d/*
What command will display the lines in the file /etc/login.defs that do not start with #

Answer: grep -v '^#' /etc/login.defs
What command will display a list of users whose login shell is /bin/bash. (Recall that the login shell is the last entry in the line for each user in the file /etc/passwd).

Answer: grep /bin/bash$ /etc/passwd