Shell Programming and Scripting

I don't know enough about SED to know if there is a problem with the SED script.

One example of what I am trying to do is as follows:


Let say I wanted to add a user alias line to the sudoers file such as:

User_Alias SOME_ADMINS = user1

At the start of that section of the file, is the heading that tells what section it is:

# User alias specification

I would want to search for this headding, and add the user alias line after that, while not deleting anything else in the file.

Someone gave me this perl solution:

Code:

perl -pi.old -e 's/(localhost)(.*)/$1\n$2\nnew\nlines\nhere/' file1 file2 file3

What this example does is search for the string 'localhost', moves the existing text on the line after the string down a line, and inserts the new lines. It does this for 3 files( file1, file2, and file3). I tested this out like so:

Code:

perl -pi.old -e 's/(#Section 2)(.*)/$1\n$2\It Worked!!!/' file1

This was the result I found when I looked at file1:

Before:

#Section 1
This is some stuff I am typing in this file for space.

#Section 2


After (I did it several times):

#Section 1
This is some stuff I am typing in this file for space.

#Section 2
It Worked!!!
It Worked!!!
It Worked!!!
It Worked!!!
It Worked!!!



The problem comes when I try to enter this:

Cmnd_Alias EPROV_ADMIN_CMDS = /usr/sbin/groupadd, /usr/sbin/groupdel, /usr/sbin/groupmod, \
/usr/bin/last, /usr/bin/listusers, /usr/sbin/logins, \
/usr/sbin/usermod, /usr/sbin/useradd, /usr/sbin/userdel, \
/usr/bin/passwd, /usr/bin/ypmatch, /usr/bin/yppasswd, \
/usr/sbin/ypcat, /usr/bin/login

What would be the best way to enter this? In other words, I need to be able to enter absolute paths to files.

As I stated above, it may not be the best approach. 'sed' searches for [search string] and replaces it with [replace string]

As per your requirement, you want the search string as well as the replaced string on the next line.

Note: if you have many replacements in a file make a temp file [sed_file] and input in it the following entries --
s/[search string1]/"[search string1] \n [replace string1]"/g
s/[search string2]/"[search string2] \n [replace string2]"/g

save this file and to make the global replacement in any file (input_file) run the following command -

sed -f sed_file input_file.

The sed command here will look for replacements from sed_file and make proper changes in the input_file.
Let me know if this helps.

Abhi.

Code:

change="User_Alias SOME_ADMINS = user1"
awk -v c="$change" '{print}
/User alias specification/{print c}
' "file" > temp
mv temp file

But will this work with the list of absolute path names above? Please help!!

Thanks, I'll give this a try.

This has been working great. I found out that the awk argument can't take more than 399 bytes. About to find out how scalable it is.