Commands

• set -o vi to set the vi editing mode

• clear screen ESC to enter vi editing mode CTRL-L

• put # at the begning of line to put that line to history file

• CTRL-U to erase whole line

• CTRL-S to stop sending the typing characters and buffer them, CTRL-Q to resume and send the buffered keys

• CTRL-D to terminate the inputs

• !! to repeat the last command

• source scriptname this cause the commands in the script to be read and run as if you typed them in

script

• $* parameters in one string

• $@ parameters in seperate double quoted string

• $# number of parameters

• $? the exit status of last command that ran

• must use ${10} for the tenth of of positional parameter

string operators

• ${varname:-word} if varname exists and isn’t null, return its value; othewise return word.

• ${varname:=word} if varname exists and isn’t null, return its value; othewise return set it to word and return word.

• ${varname:+word} if varname exists and isn’t null, return word; othewise return null return word.

• ${varname:?message} if varname exists and isn’t null, return word; othewise print message and abort current command or script

-${variable#pattern} if the pattern matches the begining of the variable’s value, detel the shortest part that matches and returne the reset

-${variable##pattern} if the pattern matches the begining of the variable’s value, detel the longest part that matches and returne the reset