topic Re: Script Help in Operating System - Linux

Script Help

Patrick Murphy — Thu, 09 Nov 2006 12:09:53 GMT

I have a file with contains many lines with the work RESTART separated by other stuff. It is like this:

stuff
RESTART 0
stuff
stuff
RESTART 0
stuff
stuff
RESTART 0
stuff

In need to locate the last RESTART in the file and change the zero that follows it to a 2. All other lines with RESTART should remain unchanged. Please no Perl solutions.

Can someone help?

Re: Script Help

Jonathan Fife — Thu, 09 Nov 2006 12:44:07 GMT

Quick n dirty:

lastline=$(grep -n RESTART filename| tail -1 | cut -d: -f1)
awk -vll=$lastline '{if (NR==ll) print "RESTART 2"; else print $0}' filename

Re: Script Help

Zinky — Thu, 09 Nov 2006 13:14:39 GMT

Here's a plain and simple solution using "ed" - the standard UNIX editor:

Put in a script:

ed - file <

Re: Script Help

Sandman! — Thu, 09 Nov 2006 13:40:56 GMT

Here's a way to do it with ex(1):

# ex -s +"$(sed -n '/RESTART/=' infile)s/0/2/p | x" infile

~cheers

Re: Script Help

Hein van den Heuvel — Thu, 09 Nov 2006 13:45:35 GMT

It's tempting to make tow passes through the file, like Jonathan shows. AWK could do that readily.

If it is not too much data (less than 10MB?) then why not suck it into an array, and remember the element with the last 'RESTART'. At end fix that element and print all:

awk 'END {l[r]="RESTART 2"; while (i++ < NR) { print l[i]}} {l[NR]=$0} /^RESTART 0/{ r=NR}' old.txt > new.txt

Good luck,
Hein.

Re: Script Help

Zinky — Thu, 09 Nov 2006 13:51:03 GMT

ed - file <

Re: Script Help

Patrick Murphy — Thu, 09 Nov 2006 13:55:21 GMT

Thanks Jonathan it worked great.

Re: Script Help

Patrick Murphy — Thu, 09 Nov 2006 13:56:52 GMT

Jonathan's work the best for my situation. Thanks all for your help.