Wildcards in SED

HealthyGuy · #1 (**permalink**) 09-27-2006

Hi Folks

Quick one I can't seem to figure out..

I need to replace a string such as "From here.....to here".

I would think the command would look like:
sed 's/From here*to here/new text/g' or
sed 's/From here\*to here/new text/g'

But it's not working for me.

Thanks in advance

vgersh99 · #2 (**permalink**) 09-27-2006

Code:

echo 'aksjfhd from here fooo asdlfkjaslkfjd to here aslfjdlaksjdf' | sed 's/from here.*to here/OVER THERE/'

anbu23 · #3 (**permalink**) 09-27-2006

* in regular expression will match any number (or none) of the single character that immediately precedes it

Code:

sed 's/From here*to here/new text/g'

This regular expression From here*to here will match
From herto here
From hereto here
From hereeto here
...

\ Usually, turn off the special meaning of the following character

Code:

sed 's/From here\*to here/new text/g'

This regular expression From here\*to here will match
From here*to here

try this

Code:

sed 's/From here.*to here/new text/g'

Corona688 · #4 (**permalink**) 09-27-2006

You might want to use the '-r' option to tell sed to use extended regular expressions. Basic sed regexes are quite limited.

Second, regular expressions work differently in sed than they do in a shell. * doesn't mean anything by itself, it's a modifier for something else. First you tell it what expression you want to match, then optionally, how many of them you want to match. An expression can be a single letter, a set of letters, or something in brackets.

A by itself just matches the letter A, like you'd expect.
[ABC] by itself just matches the letter A, B, or C.
A* tells it to match 0 or more A characters.
[ABC]* tells it to match 0 or more characters among A, B, C.
[A-Z]* tells it to match 0 or more characters among A, B, C, ..., Z.
[^A]* tells it to match 0 or more characters that aren't A.
(ABC)* tells it to match 0 or more repititions of "ABC".

* is not the only modifier:

A+ tells it to match 1 or more A characters.
A? tells it to match 0 or 1 A characters.
A{4} tells it to match precisely 4 A characters.

aigles · #5 (**permalink**) 09-27-2006

The -r option is not available on all Unix flavour.
AIX sed doesn't support this option.

Jean-Pierre.

ghostdog74 · #6 (**permalink**) 09-27-2006

Alternative , without regular expression

Code:

#!/usr/bin/python
string = "some text in front From here in the middle to here at the end"
fromindex = string.index("From here")
toindex = string.index("to here")
tobeReplace = string[ fromindex : toindex + len("to here") ]
string.replace( tobeReplace , "new text")

Output:

Code:

'some text in front new test at the end'

More UNIX and Linux Forum Topics You Might Find Helpful
Thread	Thread Starter	Forum	Replies	Last Post
Use wildcards in a script	emferrari	Shell Programming and Scripting	13	03-07-2008 04:14 AM
wildcards NOT	C3000	UNIX for Dummies Questions & Answers	5	11-21-2007 07:19 AM
ls with wildcards	benu302000	UNIX for Dummies Questions & Answers	10	06-29-2005 01:53 PM
wildcards	benu302000	UNIX for Dummies Questions & Answers	3	06-29-2005 12:10 PM
Wildcards in VI	peter.herlihy	UNIX for Dummies Questions & Answers	8	01-08-2002 04:27 AM

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode	Rate This Thread: