Sed append text to end of line if line contains specific text? How can this be done?

helptonewbie · 11-19-2008, 11:10 AM

Hi All,
I'm trying to get sed to add some text to the end of a line if that line contains a specific piece of text.

Quite simple i have a script...
echo blah
df -h
echo blah1
cd /usr/share
echo blah2
ls -al
echo blah1

And i want to use sed (i think is probably right for the job) to add text to the end of all the lines that are 'echo'

I've seen that you can :-
sed 's/$/text/' filename

But that appends to every single line i want to do something like
sed 's|echo*$|>> /var/log/output_to_log.txt|' filename

As you can see i want all the echo's to send out to a log, in the script i've already created but at the moment the echo's just send to stout, and i could run the script with filename 2>&1 /var/log/output_to_log.txt, but i'm trying to do it this other way.

Any ideas?
Cheers,
MJ

makyo · 11-19-2008, 11:37 AM

Hi.

This works for me:

Code:

#!/bin/bash -

# @(#) s1       Demonstrate append text to end of selected lines.

echo
echo "(Versions displayed with local utility \"version\")"
version >/dev/null 2>&1 && version "=o" $(_eat $0 $1) sed
set -o nounset

echo
echo " Results:"
cat <<EOF |
echo blah
df -h
echo blah1
cd /usr/share
echo blah2
ls -al
echo blah1
EOF
sed '/^echo/s|$| >> /var/log/output_to_log.txt|'

exit 0

Producing:

Code:

% ./s1

(Versions displayed with local utility "version")
Linux 2.6.11-x1
GNU bash 2.05b.0
GNU sed version 4.1.2

 Results:
echo blah >> /var/log/output_to_log.txt
df -h
echo blah1 >> /var/log/output_to_log.txt
cd /usr/share
echo blah2 >> /var/log/output_to_log.txt
ls -al
echo blah1 >> /var/log/output_to_log.txt

The page http://www.grymoire.com/Unix/Sed.html is often mentioned as useful for learning sed ... cheers, makyo

Disillusionist · 11-19-2008, 11:43 AM

Deleted as makyo's example:

sed -i '/echo/s|$| >> /var/log/output_to_log.txt|' filename

is more relevant and elegant.

helptonewbie · 11-19-2008, 01:26 PM

Sweet thanks guys both ideas work great. And great website not seen that one before.. cheers
MJ