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Vidar Holen edited this page Sep 17, 2021 · 2 revisions

In POSIX sh, echo flags are undefined.

Problematic code:

#!/bin/sh
echo -ne 'Foo:\tBar'

Correct code:

Rewrite in terms of the more robust and standardized printf:

#!/bin/sh
printf 'Foo:\tBar'

Rationale:

echo has historically behaved differently on different systems. Use printf instead to ensure compatibility between shells.

Exceptions:

If you only intend to target systems that supports this feature, you can change the shebang to a shell that guarantees support, or ignore this warning.

You can use # shellcheck disable=SC3000-SC4000 to ignore all such compatibility warnings.

Related resources:

  • Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!

ShellCheck

Each individual ShellCheck warning has its own wiki page like SC1000. Use GitHub Wiki's "Pages" feature above to find a specific one, or see Checks.

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