Shell commands notation
Shell
echo - $$
– Displays current shell process$?
– Prints the exit value of the command to the screenExit code 0
– Means command completed successfully$!
– PID of last job run in background$*
– Expands all parameters passed$$
– Contains current process ID$@
– Each passed parameter expands to a different word$0
– Show the name of the shell or script$_
– Set at shell startup and contains the absolute file name of the shell/script being execute; expands last argument to the previous command