perl 替换为 bash 变量

Question

有人可以解释一下，为什么 perl 不替换正则表达式：

root@machine08:~# VERSIONK8S='${VERSION_KUBERNETES:-1.23.3-00}'
# with sed as i want it
root@machine08:~# sed -e "s/^VERSIONK8S=.*/VERSIONK8S=${VERSIONK8S}/g" /root/coding/k8s-setup/allnodes_basic_setup.sh | grep ^VERSIONK8S=
VERSIONK8S=${VERSION_KUBERNETES:-1.23.3-00}
# with perl not exactly as i want it
root@machine08:~# perl -pe "s/^VERSIONK8S=.*/VERSIONK8S=${VERSIONK8S}/g" /root/coding/k8s-setup/allnodes_basic_setup.sh | grep ^VERSIONK8S=
VERSIONK8S=-e

Answer 1

来自 Perldoc：

If the delimiter chosen is a single quote, no variable interpolation is done on either the PATTERN or the REPLACEMENT. Otherwise, if the PATTERN contains a $ that looks like a variable rather than an end-of-string test, the variable will be interpolated into the pattern at run-time.

Perl 尝试将替换字符串 ${VERSION_KUBERNETES:-1.23.3-00} 扩展为以 $ 开头的 perl 变量，但失败了。为避免扩容，请尝试：

perl -pe "s'^VERSIONK8S=.*'VERSIONK8S=${VERSIONK8S}'g" /root/coding/k8s-setup/allnodes_basic_setup.sh | grep ^VERSIONK8S=

使用单引号作为分隔符而不是斜杠，例如 s'pattern'replacement'.

perl 替换为 bash 变量

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