(or "In dash, ... is not supported." when using
dash
)
#!/bin/sh
x='test'
echo "${x^^[t]}"
The easiest solution is to switch to a shell that does
support name matching prefixes, like bash
:
#!/bin/bash
x='test'
echo "${x^^[t]}"
Alternatively, use external tools like tr
for case
conversion
#!/bin/sh
x='test'
echo "$x" | tr 't' 'T'
Case modification in parameter expansion (e.g., ${x^^}
,
${x,,}
, ${x^}
, ${x,[pattern]}
) is
a bash and ksh extension. dash and POSIX sh do not support it.
If you only intend to target shells 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.
ShellCheck is a static analysis tool for shell scripts. This page is part of its documentation.