13,420
edits
Changes
→Using Variables in Shell Scripts
[[Image:positional.png|thumb|right|220px|Examples of using '''positional''' and '''special''' parameters.]]A '''positional parameter''' is a variable within a shell program; its value is set from an argument specified on the command line that invokes the program.
Positional parameters are numbered and their values are accessed by using a preceding "'''$'''" (eg. '''$1''', '''$2''', '''$3''', and so onetc.). The positional parameter '''$0 ''' refers to either the name of shell where command was issued, or name of shell script being executed. If using '''positional parameters''' greater than '''9''', then you need to include number within braces.<br>Examples: '''echo ${10}''', '''ls ${23}'''
The '''shift''' command can be used with positional parameters to shift positional parameters<br>to the left by one or more positions.
There are a few couple of ways to assign values as positional parameters:
:*Use the '''set''' command with the values as argument after the set command
:*Run a shell script containing arguments
