Shell Scripting: Linux variables

Linux variables have the prefix $. Variables that will be useful in shell scripting are listed below. $$ Process ID number of the shell in execution $? Variable indicating Exit status (from the last command that got executed) $* Entire argument string in the command line (excluding script name) $# Number of arguments in the command line (not counting the shell script name) To access arguments passed to a script, following variables are used. $0 Name of the program (with entire path) $1 First argument passed in the command line $2 Second argument passed in the command line $n Nth argument passed in the command line To move or shift to a specified argument in the list of arguments, "shift" command is used. For example, to shift 1 argument just type "shift" or "shift 1" and to shift to the third argument in the list type "shift 2". (more…)