Linux shell

Know it
LOVE IT
UsE IT
everything in linux can be accomplished via shell

cheatsheet

A-Z bash commands

we have Desktop environments, why use the shell?

• Exposes you to the internals of how things work in Linux
• If you can run it in the shell, you can automate it
• 99% of Linux servers WON'T HAVE A DESKTOP ENVIRONMENT if setup correctly

LS/find

• "ls" is the same as "dir" in Windows
• "find" basically does a recursive "ls" + more

ex. List all files, including hidden files, in current folder

ls -la

http://unixhelp.ed.ac.uk/CGI/man-cgi?ls

http://content.hccfl.edu/pollock/Unix/FindCmd.htm

cd

• Same as Windows
• Changes current directory

cd ~  # go home

http://unixhelp.ed.ac.uk/CGI/man-cgi?cd

Filesystem navigation/basic manipulation

cp/MV/rm/mkdir

Copy/move/remove files

No "rename" in Linux, use "mv"

rm -rf  # recursively remove files
mkdir -p ~/projects/new_project
mv jeo.txt joe.txt  # rename file
cp ~/.ssh/known_hosts ~/hosts.bak

cat/touch

"Concatenate" == echo file content to standard out (stdout)

http://www.tecmint.com/13-basic-cat-command-examples-in-linux/

"Touch" == create empty file or update last-modified file date/time

less/more

• Pause output at page boundaries
• "less" is more versatile

http://linux.about.com/library/cmd/blcmdl1_less.htm

pipes and redirection

A pipe "pipes" the output from one command into the input of another command

cat joe.txt | sort

streams => STDIN/STDOUT/STDERR

echo "Hi, there!" > joe.txt

http://www.ibm.com/developerworks/library/l-lpic1-v3-103-4/

streams

ps

ps -aux | grep PROC

^ list all processes and filter down to process that contain "PROC" in their listing

http://linuxcommand.org/man_pages/ps1.html

kill and signals

• Sends a signal to a process
• Signal 9 == forcefully kill the process via kernel
• Sends TERM (stop) to process by default, if process is hung it might not actually self-terminate

kill -9 PROCESSNUMBER

^ process with PROCESSNUMBER is now dead for sure

http://en.wikipedia.org/wiki/Unix_signal

processes

killall

• killall firefox # processes named firefox sent TERM signal

• killall -9 firefox # tell kernel to kill all firefox processes

https://www.digitalocean.com/community/tutorials/how-to-use-ps-kill-and-nice-to-manage-processes-in-linux

http://linux.die.net/man/1/killall