Pattern matching in a zsh conditional expression
[ $x = '*test*' ]
tests whether the string resulting from expanding $x
, which is text
, is equal to the string resulting from expanding '*test*'
, which is *text*
.
To test whether the value of the variable x
matches the pattern *test*
, you need to use the =
or ==
operator of zsh conditional expressions, which are written within double brackets [[ … ]]
. Furthermore special characters in the pattern must be unquoted, otherwise they stand for themselves. Thus:
if [[ $x == *test* ]]; then …
The syntax of conditional expressions is similar to the syntax of expressions that you can use within single brackets [ … ]
, but not identical. [
is parsed like an ordinary command; in fact, it's a built-in command with a one-character name, which is identical to the test
builtin except that [
requires an additional argument at the end which must be ]
. [[ … ]]
is a distinct grammatical construct, which allows it to have shell special characters inside. [ $x = *test* ]
would expand *test*
to the list of matching file names (globbing) and the test
builtin would end up parsing the result of that. [[ $x = *test* ]]
parses *test*
as part of conditional expression parsing which does not invoke globbing.
*test*
is not a valid regex pattern. The *
is a repetition operator and needs something to repeat. It's very likely you want .*test.*
, although that isn't necessary with regex since it is not anchored by default. You could just look for test
However you cannot match regex patterns with the =
operator, you need =~
.
precmd () {
local x=test
if [[ $x =~ test ]]; then
echo 'hello'
fi
}