Linux Basic
Linux Shortcut Key
Auto complete for directory and filenames: Tab
History Search: CTRL-R
Clear Screen: CTRL-L
Abandon Current Command: CTRL-C
Linux Account Stuff
Create a user: useradd -d [home_dir] [login]
e.g. create a non-root account useradd -d /home/fred fred
$ means non-root # means root
Changing password: passwd [login_name]
Changing to root:
sudo su -[type your password]
Check your current account: whoami
Exit your most recent su: exit
More details about your current user id and privileges: id
File System
Move around the file system: cd [directory-name]
Up on level: cd ..
See your current path: pwd
Jump to your current account home directory: cd ~
List directory: ls
show all files: ls -a
show details: ls -l
Make directory: mkdir
Search in a local database for a program: locate whoami
Update the local database: updatedb
Find file: find [directory_to_search] [search criteria]
e.g. find the whoami program find / -name whoami
File editor: vi, gnu-emacs, pico, mcedit, gedit
e.g. gedit [filename]
head command shows the start of a file (line is specified by -n [n] option): head -n [line] [filename]
tail command shows the end of a file: tail -n 2 /etc/passwd
view output larger than a single screen: less [test_file]
Type q to quit less
other usage: ls /dev | less
Running Program
See all paths: echo $PATH
Look at the paths where program are run from: which ls
Temporarily adding a path: PATH=$PATH:/[another_directory]
Permanently change your path: edit the ~/.bash_profile
Looking at running processes: ps aux or ps aux | less
Task Manager: top
Pause a running program and get back the shell: CTRL-Z
To start the program again in the background: bg
To start the program again in the foreground: fg
Run a program/command and send it to the background: find /-name ls &
See jobs run in background: jobs
Bring one of the jobs (default is recent job) into the foreground: fg [job_number]
Networking Stuff
Set your network interface options:
/etc/network/interfaces
Make your changes happen (as root):
service networking restart
See your interface configuration:
ifconfig
lo is local loopback interface, eth0 is standard ethernet interface
Send ICMP Echo Request:
ping [IP Address]
Looking at network usage:
netstat -nap
Better:
netstat -nap | less
Note that various TCP and UDP po1ts are shown as LISTENING. These are waiting for a connection. Others may indicate that they are ESTABLISHED. These have existing connections.
Building Tools
untar a file
tar xvf [archive.tar]
untar a file end with tar.gz or tgz
tar xvfz [archive . tar.gz or archive . tgz]
A script is included with some tools to properly configure your system
make program then compiles it
make install command then installs the components
. /configure make make install
Note: Some tools don't have a "configure" script. For these, you just run the make command.
Other command
To look for a given string in a set of files in a directory: grep [root] *
Manual: man ls
Info: info ls
Look for hint of an command: whatis ifconfig
Search for topics and the command related to that topic: apropos network
Equivalent to the above: man -k network
Shutdown and Reboot
Shutdown and halt: shutdown -h now
Shutdown and reboot: shutdown -r now or reboot