Envsubst - Revision history

Leo: Updated categories

2021-12-30T01:32:17Z

Updated categories

← Older revision		Revision as of 01:32, 30 December 2021
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	{{Navbox Linux}}		{{Navbox Linux}}
	[[Category:Linux]]		[[Category:Linux]]
			[[Category:LinuxUtilities]]

Leo at 00:10, 10 December 2021

2021-12-10T00:10:57Z

← Older revision		Revision as of 00:10, 10 December 2021
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	<code>envsubst</code>, short for '''env'''ironment '''subst'''itution, makes it easy to substitute environment variables in a text file. This is a simple way to template files.		<code>envsubst</code>, short for '''env'''ironment '''subst'''itution, makes it easy to substitute environment variables in a text file. This is a simple way to template files.

	== Usage ==		==Usage==
	<code>envsubst</code> can replace variables in the form of <code>${VAR}</code> and <code>$VAR</code> with the value defined as an environment variable. The template file is piped to <code>envsubst</code>.		<code>envsubst</code> can replace variables in the form of <code>${VAR}</code> and <code>$VAR</code> with the value defined as an environment variable. The template file is piped to <code>envsubst</code>.

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	\| lang = bash		\| lang = bash
	}}		}}
	~~To use default variables, you can use~~
			{{Navbox Linux}}
			[[Category:Linux]]

Leo: Created page with "`envsubst`, short for '''env'''ironment '''subst'''itution, makes it easy to substitute environment variables in a text file. This is a simple way to template files..."

2021-12-10T00:09:17Z

Created page with "<code>envsubst</code>, short for '''env'''ironment '''subst'''itution, makes it easy to substitute environment variables in a text file. This is a simple way to template files..."

New page

<code>envsubst</code>, short for '''env'''ironment '''subst'''itution, makes it easy to substitute environment variables in a text file. This is a simple way to template files.

== Usage ==
<code>envsubst</code> can replace variables in the form of <code>${VAR}</code> and <code>$VAR</code> with the value defined as an environment variable. The template file is piped to <code>envsubst</code>.

A simple example with one variable:
{{Highlight
| code = $ export FirstName=leo
$ echo "hello ${FirstName}" {{!}} envsubst
hello leo
| lang = terminal
}}
To save the generated output, simply redirect it to a file.
{{Highlight
| code = $ export FirstName=leo
$ echo "hello ${FirstName}" {{!}} envsubst > hello.txt
| lang = terminal
}}
While <code>envsubst</code> isn't capable of supporting more advanced shell features such as <code>${VAR:-default_value}</code>, you can still make use of it inside a shell script.
{{Highlight
| code = #!/bin/bash

## If no argument is passed, FirstName will be set to 'stranger'
FirstName="${1:-stranger}"
echo "Hello there, $FirstName" {{!}} envsubst
| lang = bash
}}
To use default variables, you can use

Envsubst - Revision history

Leo: Updated categories

Leo at 00:10, 10 December 2021

Leo: Created page with "envsubst, short for '''env'''ironment '''subst'''itution, makes it easy to substitute environment variables in a text file. This is a simple way to template files..."

Leo: Created page with "`envsubst`, short for '''env'''ironment '''subst'''itution, makes it easy to substitute environment variables in a text file. This is a simple way to template files..."