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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 S001. Use GitHub "Pages" feature above to find a specific one, or see Checks.

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