Edit the file in shell script

ETC Homework & Coursework Questions
1

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  1. The problem statement, all variables and given/known data:

I am trying to automate hadoop installation procedure using shell script. It involves go to perticular directory and add some more lines to the file /etc/sysctl.conf. How this can be done?

  1. Relevant commands, code, scripts, algorithms:

Need to edit /etc/sysctl.conf while running script.

  1. The attempts at a solution (include all code and scripts):
    I have tried it using vi and i am not able to do this.

  2. Complete Name of School (University), City (State), Country, Name of Professor, and Course Number (Link to Course):
    University of Houston , Texas, USA, Dr. Deniz Gurkan,ELET6300

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2

The vi utility is an interactive editor, not a scripting editor. Look at the man pages for ex , ed , and sed for utilities that are intended to be used to edit files in scripts.

3

Another thing to consider in your script (maybe some extra credit :wink: ): Does it create a way to undo the change you are making to sysctl.conf? Consider taking a backup first...

4

Assuming that I have read the question correctly.

One solution would be to create a file called say /etc/sysctl.conf.append with "vi" or editor of the day, containing ONLY the new lines.

Then append the new lines to the old file using good old "cat".

cat /etc/sysctl.conf.append >> /etc/sysctl.conf

In the commercial world we would save the old version of the file (and it's permissions) before changing it. For example:

cp -p /etc/sysctl.conf /etc/sysctl.conf.180414

---------- Post updated at 02:40 ---------- Previous update was at 02:35 ----------

If we go one step further it is possible to automate the entire process by creating the "append" file in the shell script.

echo "line 1" > /etc/sysctl.conf.append
echo "line 2" >> /etc/sysctl.conf.append
echo "line 3" >> /etc/sysctl.conf.append

As we know nothing about your computer or its Operating System or Shell, this is a generic answer. In some shells the "echo" needs replacing.