SC3011 – ShellCheck Wiki

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In POSIX sh, here-strings are undefined.

Problematic code:

#!/bin/sh
wc <<< "$1"

Correct code:

#!/bin/sh
wc << EOF
$1
EOF

Rationale:

Your script uses a shell feature not supported by the shebang. Either rewrite the script to be portable, or change the shebang to explicitly require a shell like Bash. In this specific case, the here-string can be replaced by a single-line here document as shown.

Exceptions:

None

Related resources:

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

ShellCheck is a static analysis tool for shell scripts. This page is part of its documentation.