What do 0 1 2 mean in shell script

Question

I often come across     0  1  2 etc     in shell scripting  what I know is that    returns the exit status of the last command  echo  this will return 0  echo      but what do the others do  what are they called and is there more  perhaps like  3  4  5

User · Answer

They are called the Positional Parameters.

3.4.1 Positional Parameters

A positional parameter is a parameter denoted by one or more digits, other than the single digit 0. Positional parameters are assigned from the shell’s arguments when it is invoked, and may be reassigned using the set builtin command. Positional parameter N may be referenced as ${N}, or as $N when N consists of a single digit. Positional parameters may not be assigned to with assignment statements. The set and shift builtins are used to set and unset them (see Shell Builtin Commands). The positional parameters are temporarily replaced when a shell function is executed (see Shell Functions).

When a positional parameter consisting of more than a single digit is expanded, it must be enclosed in braces.

User · Answer

These are positional arguments of the script   Executing    script sh Hello World   Will make   0     script sh  1   Hello  2   World   Note  If you execute   script sh   0 will give output   script sh but if you execute it with bash script sh it will give output script sh

[bash] What do $? $0 $1 $2 mean in shell script?

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