Variable Substitution
I Found This on Shell Script, in Variable Substitution Option Using Cap Symbols Can Anyone Explain the Logic of This Nf=${F: Gs^__^/^} for F in Notes__*...
I found this on shell script, in variable substitution option using cap symbols can anyone explain the logic of this nf=${f:gs^__^/^}
for f in notes__* books__*; do
nf=${f:gs^__^/^}
perl -p -e $f > /home/bob/$nf
done
Any help would be great, thanks.
1 Answer
You tagged your question both bash and zsh, however AFAIK the :s syntax is only supported in zsh (borrowed from csh). The bash equivalent would be ${f//__/\/} - which is also supported in zsh (and borrowed from ksh).
:gs introduces a global substitution inside the parameter expansion. ^ is an arbitrary (user-supplied) delimiter - the usual choice would be / but in this case it appears the replacement text is / so ^ is chosen instead. So given
f=notes__foo__bar
${f:gs^__^/^} globally replaces __ with /:
% echo ${f:gs^__^/^}
notes/foo/bar
Refer to man zshexpn for further details.
Marcus Vance is a cybersecurity auditor and technology writer dedicated to educating the public about online safety, data privacy regulations, enterprise security, and emerging cyber threats.
