why this does not match..?
sed -e '/--Updated?[[:space:]]+Date/d' inputfile
this..:
--Updated Date: 2013-11-06 15:32:13
d? is because sometimes I have Update Date, and sometimes Updated Date.
for removal? I have tried with \s too, not working.
you need to use the -r parameter.
try use
sed -r '/--Updated?[[:space:]]+Date/d' inputfile
updating answer
When you use sed '/something/d' , every line that match with this will be deleted.
-r - the parameter -r is use extended regular expressions .
Inside the expression have 2 regular expressions.
[[:space:]] - Match with all whitespace characters, including line breaks
? - optional
+ - one or more times.
SO, the command sed will delete every line that match with --updated and than one or more whitespace character and than Date but because of the ? the character d is optional. like:
--Updated Date: 2013-11-06 15:32:13
--Updated Date: 2013-11-06 15:32:13
--Updated Date: 2013-11-06 15:32:13
--Update Date: 2013-11-06 15:32:13
To do this using POSIX basic regex, the closest I can come is:
sed '/--Updated*[[:space:]][[:space:]]*Date/d' inputfile
Unfortunately there is no real substitute for ?, so a * is used which would also match multiple ds. The + however can be replaced by simply repeating the pattern an using a * for the second repetition.
Actually the way to get the equivalent effect of the extended expressions is to use two patterns:
sed \'
/--Updated[[:space:]][[:space:]]*Date/d
/--Update[[:space:]][[:space:]]*Date/d
' inputfile
-r? I am using GNU sed, so I should be safe?
Commented
Mar 28, 2014 at 15:32
sed will always be used, then you will be fine to use the extended expressions. If you will run it on another system, eg on OSX, then the -r option may not be in the default sed.
[d ]* would be a little more explicit, if not by much. It is definitely tricky.
sed now has two directives to check per line. Generally though, at least in my experience this is a non-issue, as sed is probably the fastest solution in any case that involves editing. Grep might be faster in this case though if you use -v. The only times i've been disappointed with sed is when ive had a choice between using it with two outs and the w directive or tee and two concurrent greps. The latter seems always to win out.
With gnu sed 4.2.2 on cygwin, add the -r flag:
'--Updated Date: 2013-11-06 15:32:13'|sed -r -e '/--Updated?[[:space:]]+Date/d'
prints no output. -r turns on extended regular expressions so ? and + will work like you expect. The reference for extended regular expressions I use most points out that ? and + have to have a leading backslash in basic regular expressions (the default) in order to have their special meaning.
