SED from a shell script - driving me up the wall!!!

[cbillson]

why does this work

sed -e 's/.*Jun 19//' myfile

And this not

mmm=Jun
dd=19
sed -e 's/.*$mmm $dd//' myfile


both being ran from a shell scrip, not CLI

myfile:

< Jun 19 00:00:00 some data

I've tried quotes round it, no joy, i'm using *. as i'd like to lose the < too.

[steeldriver]

It's nothing to do with sed specifically - single quotes prevent expansion of shell variables, try double quotes instead

sed -e "s/.*$mmm $dd//" myfile

Be aware that this *can* allow the shell to expand things you *don't* want it to in certain circumstances

[SeijiSensei]

Because you are using single quotes. That tells bash to treat the quoted string as a literal. Try using double quotes (") instead. Then bash will replace the variables with their values.

[cbillson]

ahh, thank-you very much - you learn something new every day..