Shell Script Error: ‘declare: not found’ – Causes and Solutions

bashshell-builtin

Here is a simple example showing that using declare in a script the script will not run, while sourcing the script will:

$ cat /tmp/new
#! /bin/sh
declare -i  hello
$ chmod a+rwx /tmp/new
$ /tmp/new
/tmp/new: 3: declare: not found
$ source /tmp/new
$

I wonder why directly running the script doesn't work, while sourcing it does? How can I make the first one work? Thanks!

Best Answer

declare is a builtin function and it's not available with /bin/sh, only with bash or zsh (and maybe other shells). The syntax may differ from one shell to another. You must choose your sheebang (#!) accordingly: if the script needs to be run by bash, the first line must be

#!/bin/bash

or

#!/usr/bin/env bash
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