+=
is
undefined.(or "In dash, ... is not supported." when using
dash
)
var="Hello "
var+="World"
var="Hello "
var="${var}World"
Using +=
to concatenate to an existing variable is a
ksh/bash extension. For POSIX sh or dash, write out the full expression.
Be careful to use braces if the text you append could be confused for a
variable (as in the example, to avoid $varWorld
being
interpreted as ${varWorld}
)
None.
ShellCheck is a static analysis tool for shell scripts. This page is part of its documentation.