sed -i problems

[cj13579]

hi all,

I have a script that I am running and part of it inserts some lines into a config file using sed:

sed -i '19 i\  stuff to insert' ./config.yml

This works on one of my ubuntu boxes but not the other and I can't for the life of me work out why! The filesystem permissions look to be the same:

working:

$ ls -l | grep config.yml
-rwxr-xr-x 1 www-data www-data   3301 2012-04-19 19:00 config.yml

not working:

$ ls -l | grep config.yml
-rwxr-xr-x 1 www-data www-data    281 2012-04-19 14:02 config.yml

When I run the sed command from the command line I get no error message and the return codes seems to be fine. However, I don't see any stuff in the file:

$ sed -i '19 i\  stuff to insert' ./config.yml
$ echo $?
0
$

I have even checked to make sure that they are running the same version of sed:
working:

$ uname -a
Linux q2server 2.6.32-38-generic-pae #83-Ubuntu SMP Wed Jan 4 12:11:13 UTC 2012 i686 GNU/Linux
$ sed --version
GNU sed version 4.2.1

not working:

$ uname -a
Linux ubuntu 2.6.32-21-generic-pae #32-Ubuntu SMP Fri Apr 16 09:39:35 UTC 2010 i686 GNU/Linux
$ sed --version
GNU sed version 4.2.1

Any help as always is greatly appreciated!

[papibe]

Hi cj13579.

My first guess is that one that doesn't work hasn't more that 19 lines.

Could you post the result of this commands on both machines?

wc -l config.yml

Regards.

[cj13579]

Ah ha! Genius - that was exactly the problem. To get round it I just stuck a little condition in to add another line fist:

if [[ $x -ge $y ]] ; then
   sed -i '$ a\ ' $CONF
fi

I had another one similar later on in the script where I was trying to work with an empty file. I just changed the methodology if and when there are no lines in the file:

x=$(wc -l $APP_HOME/config.txt | cut --fields=1 --delimiter=' ')
if [[ $x -eq 0 ]] ; then
   echo "$sm:$loc/$star" >> $APP_HOME/config.txt
else
   sed -i "$ a\
   $sm:$loc/$star" $APP_HOME/config.txt
fi

Many thanks for your great help and swift response.