sed RegEx problems

InJesus · 01-11-2007, 04:21 PM

I'm trying to match 0000-00-00 00:00:00 then surround it with quotes using sed

sed -i 's/\(\d{4}\-\d{2}\-\d{2} \d{2}\:\d{2}\:\d{2}\)/"\1"/g' regExTest

I've tried a thousand variations can't seem to get it to work, Even if I simplify it just to see if I can get it going with something like 's/\(\d{4}\)/\1'/g' nothing, i'm baffled.

Thanks,

J

wjevans_7d1@yahoo.co · 01-11-2007, 05:41 PM

I haven't double-checked your syntax, but if you're using {4} and {2} and the like, you're using extended regular expressions. So you need to use the -r switch in there:

sed -i -r [and so forth]

For more sed details, don't miss:

man sed

Hope this helps.

InJesus · 01-11-2007, 05:42 PM

yes, I've tried the -r, It's still not working.

wjevans_7d1@yahoo.co · 01-12-2007, 06:02 AM

I'm actually working on two Slackware distributions here: my wife's, and my own. My wife's is Slackware 11; my own is Slackware 9.1. My system has an older version of sed, which doesn't even have the -i and -r switches. My wife's system has both, so I've been using hers to pursue your question.

But I don't have access to my wife's system at this point, so help me out here.

It looks as though the regular expression isn't matching. What does "man sed" on your system say about regular expressions? (Search the whole thing for "reg".)

colucix · 01-12-2007, 08:29 AM

The following matches on my system:

Code:

# cat regExTest
string 0000-00-00 00:00:00 string

# sed 's/\([0-9]\{4\}-[0-9]\{2\}-[0-9]\{2\}\ [0-9]\{2\}:[0-9]\{2\}:[0-9]\{2\}\)/"\1"/g' regExTest
string "0000-00-00 00:00:00" string

# sed 's/\(0\{4\}-0\{2\}-0\{2\}\ 0\{2\}:0\{2\}:0\{2\}\)/"\1"/g' regExTest
string "0000-00-00 00:00:00" string

The former to match any digit, the latter to match exactly zeros.

InJesus · 01-12-2007, 11:35 AM

That's pretty much what I had to do, I ended up just going 's/\([0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9] [0-9][0-9]:[0-9][0-9]:[0-9][0-9]\)/"\1"/g' although your way seems much more eligant, it only saves a few charectors. I think i must have been looking at different versons GNU does not like the \d switch for digits. Thanks for the reply guys, linuxquestions.org is good because of it.

GB
J

makyo · 01-12-2007, 11:48 AM

Hi, InJesus.

The qualifier, { minimum, maximum }, will require a different syntax depending on old or new version of sed, and on whether "-r" is specified on new versions.

Here's a short script:

Code:

#!/bin/sh

# @(#) s1       Demonstrate braces differences in sed.

echo
echo " plain braces, basic re"
echo "xxxx" |
sed 's/x{4}/1234/'

echo
echo " escaped braces, basic re"
echo "xxxx" |
sed 's/x\{4\}/1234/'

echo
echo " plain braces, extended re"
echo "xxxx" |
sed -r 's/x{4}/1234/'

echo
echo " escaped braces, extended re"
echo "xxxx" |
sed -r 's/x\{4\}/1234/'

which produces these different results:

Code:

% ./s1

 plain braces, basic re
xxxx

 escaped braces, basic re
1234

 plain braces, extended re
1234

 escaped braces, extended re
xxxx

Basically, the "-r" reverses the specialness of the "{}". I think you'll need the form which uses "\" prior to the "{}" characters on the old version of sed.

Best wishes ... cheers, makyo