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Thread: sed -i problems

  1. #1
    Join Date
    Apr 2008
    Location
    England
    Beans
    260
    Distro
    Ubuntu

    sed -i problems

    hi all,

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

    Code:
    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:
    Code:
    $ ls -l | grep config.yml
    -rwxr-xr-x 1 www-data www-data   3301 2012-04-19 19:00 config.yml
    not working:
    Code:
    $ 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:
    Code:
    $ 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:
    Code:
    $ 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:
    Code:
    $ 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!

  2. #2
    Join Date
    Feb 2009
    Location
    Dallas, TX
    Beans
    7,664
    Distro
    Ubuntu 16.04 Xenial Xerus

    Re: sed -i problems

    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?
    Code:
    wc -l config.yml
    Regards.

  3. #3
    Join Date
    Apr 2008
    Location
    England
    Beans
    260
    Distro
    Ubuntu

    Re: sed -i problems

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

    Code:
    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:

    Code:
    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.

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