Appendix E. Linux Command Quick Reference

The following list describes some of the most useful and popular Linux commands. Consult the man page for each command to learn about additional arguments and details of operation.

adduser userid

Creates a new userid, prompting for necessary information (requires root privileges).

apropos keyword

Searches the manual pages for occurrences of the specified keyword and prints short descriptions from the beginning of matching manual pages.

at time , at -f file time

Executes commands entered via stdin (or, by using the alternative form, the specified file) at the specified time. The time can be specified in a variety of ways; for example, in hour and minute format hh:mm or in hour, minute, month, day, and year format hh:mm mm/dd/yy.


Prints descriptions of jobs pending via the at command.

atrm job

Cancels execution of a job scheduled via the at command. Use the atq command to discover the identities of scheduled jobs.

bg , bg jobs

Places the current job (or, by using the alternative form, the specified jobs) in the background, suspending its execution so that a new user prompt appears immediately. Use the jobs command to discover the identities of background jobs.

cal month year

Prints a calendar for the specified month of the specified year.

cat files

Prints the contents of the specified files.

cd , cd directory

Changes the current working directory to the user’s home directory or the specified directory.

chgrp group files ,

Get Learning Debian GNU/Linux now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.