Intro to Command Line

Command Prompt

• First item in the prompt is a line representing the user name, followed by the "@" sign, the computer host name, a colon ":", the current working directory and the "$" sign.

user@ubuntuVM:~$
# current_user @ host_name : current_working_directory $
# user = current_user
# ubuntuVM = hostname
# ~ = user's home directory
# $ = logged in as a normal user

root@ubuntuVM:/home/user#
# # = logged in as the root user

whoami

• whoami - Returns the user name of the current user

user@ubuntuVM:~$ whoami
	user

• Note Linux is case-sensitive, so the commands are too.

hostname

• hostname - Returns the name of the current host

user@ubuntuVM:~$ hostname
	ubuntuVM

pwd

• pwd - Print working directory

user@ubuntuVM:~$ pwd
	/home/user

# ~ is shorthand for the home directory

ls

• ls - List the contents of a directory

user@ubuntuVM:~$ ls
	Desktop  Documents  Downloads  Music  Pictures  Public  snap  Templates  Videos

cd

• cd - Change working directory

user@ubuntuVM:~$ cd Downloads
user@ubuntuVM:~/Downloads$
# the current working directory changed

user@ubuntuVM:~/Downloads$ cd ..
# to go back to the parrent directory
user@ubuntuVM:~$

📌 Use only cd to go back to the current user's home directory

user@ubuntuVM:~$ cd /tmp/
user@ubuntuVM:/tmp$ cd
user@ubuntuVM:~$

alias

• alias - list bash aliases

alias
    alias alert='notify-send --urgency=low -i "$([ $? = 0 ] && echo terminal || echo error)" "$(history|tail -n1|sed -e '\''s/^\s*[0-9]\+\s*//;s/[;&|]\s*alert$//'\'')"'
    alias egrep='egrep --color=auto'
    alias fgrep='fgrep --color=auto'
    alias grep='grep --color=auto'
    alias l='ls -CF'
    alias la='ls -A'
    alias ll='ls -alF'
    alias ls='ls --color=auto'

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