sed regex one or none '?'

casperdaghost · 06-20-2012, 11:11 PM

Yeah So i want to get rid of the comment - I though that if you use '?' in the regex - that is signifies one or nothing - - so if there is one - it would replace it, and if there is not,it would just skip it.

I thought that sed used perl like regex rules.

Code:

casper@ashpcasperinit01 ~ $ grep -i casperserver  /var/ftp/*.commands | awk -F'/' '{print $4}' | sed 's/\.commands:#?//g'
casper3013.1.commands:
casper3013.1.commands:
casper3013.1.commands:
casper3013.1.commands:
casper3013.1.commands:
casper3013.1.commands:
casper3013.1.commands:#
casper3013.2.commands:
casper3013.2.commands:
casper3013.2.commands:
casper3013.2.commands:
casper3013.2.commands:
casper3013.2.commands:
default.commands:


casper@ashpcasperinit01 ~ $ grep -i casperserver  /var/ftp/*.commands | awk -F'/' '{print $4}' | sed 's/\.commands://g'
casper3013.1
casper3013.1
casper3013.1
casper3013.1
casper3013.1
casper3013.1
casper3013.1#
casper3013.2
casper3013.2
casper3013.2
casper3013.2
casper3013.2
casper3013.2

syg00 · 06-21-2012, 12:17 AM

You want regex extended - see the manpage.
Won't do what (I think) you want, but you'll get further.

grep has the option for perl regex. All regex is different ...

pan64 · 06-21-2012, 12:59 AM

sed and perl regexps are more or less similar, but surely not identical. So if you were unsure, you should read the man page.
From the other hand do not use grep|awk|sed (or similar) chains because it can be solved with one of them, for example with a single awk script. The regexps in awk are also slightly different.

Code:

awk -F/ ' /casperserver/ { gsub(".commands:#?", $4); print $4 } ' /var/ftp/*.commands

will do almost the same (not tested, just copied)

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grail · 06-21-2012, 08:32 AM

To me it would be the age old story of show us what you start with and then what you would like to finish with, as showing us what does not work is fine from the point of view that you had
a go but does little to help us help you.

krazyglue · 06-21-2012, 09:11 AM

Not 100% sure what your looking for but this should work.

Code:

grep -i casperserver  /var/ftp/*.commands |sed 's!commands:#.*!commands:!'

This looks for "commands:#" and anything after that and subs in "commands:" for it.

sycamorex · 06-21-2012, 09:44 AM

Agree with grail. No point in guessing....

We call upon the author to explain.... and provide the actual samples of the original text and the desired end output.