Re: sed with Variable Substitution in the command

[alex xmb sw ratchev]

the out perl code , would it translare & s to search-in ? or is it flat
string ? i guess \Q is for this .. dunno ..

greets ..

On Thursday, September 19, 2024, Greg Wooledge <greg@wooledge.org> wrote:

> On Thu, Sep 19, 2024 at 10:03:01 -0400, Steve Matzura wrote:
> > sed -i 's/replace-this/$with_this_variable/'
>
> The simplistic answer is "you want double quotes instead of single quotes".
>
>     sed -i "s/replace-this/$with_this_variable/"
>
> However, the problem goes a bit deeper than that.  Sed *always* uses
> regular expressions to match things.  There is no option to use a
> plain string.  Therefore, if your replace-this has any special characters
> in it (or has the *possibility* of it, e.g. if it's a variable as well),
> then you may get unpredictable results.
>
> (Slashes or newlines in the $with_this_variable content would also cause
> an issue.)
>
> <https://mywiki.wooledge.org/BashFAQ/021> suggests using perl instead:
>
>     in="$search" out="$replace" perl -pi -e 's/\Q$ENV{"in"}/$ENV{"out"}/g'
> ./*
>
> This forces a plain string match for the "in" side, so it'll work no
> matter what characters are used.
>
> There are other examples given on that page as well.
>
>