Search and delete lines matching a pattern along with comments in previous line if any

command-line-interfacescriptingshellunix-shell

I have a requirement to write a shell script in csh to search and delete lines matching a pattern along with comments in previous line if any. For example if my file has the following lines

Shell script
#this is  a test
pattern1
format1
pattern2
format2
#format3
pattern3

If the search pattern is "pattern" The output should be as follows

Shell script
format1
format2

To be more precise the lines which have the pattern and the previous line if it begins with "#" should be deleted

Thanks for the help

Best Answer

First of all nobody should ever use csh for anything - it's outdated and un- (not "under") powered. Secondly, I doubt it's up to the task. Third, it's much more likely that awk, sed or even Perl will be a much better tool for the task.

awk '/^#/ {printf line; line=$0"\n"; next} /pattern/ {line=""} ! /pattern/ {printf line; print; line=""}'

Edit: fixed script to handle comment lines correctly

Related Solutions

How to compare two directories residing in two different servers

I like to use rsync for this purpose.

For example, on ServerA run:

rsync -avnc --delete /path/to/dir/ serverB:/path/to/dir/

You can remove the -c switch if you don't need to do a checksum comparison of the files. Without it rsync will assume they are the same if they have the same size and timestamps.

Note the trailing slashes on each of the paths.

Very important: Make sure you have the -n switch otherwise rsync will start changing the contents of ServerB

Grep command to search for a pattern in multiple files and list the files ordering by date

This is much faster. Whereas the other answers grep all the files, this searches the newest ones first and stops as soon as it finds the pattern.

This one-liner captures the result in a variable:

file=$(while read file; do grep pattern "$file" >/dev/null;[[ $? ]]; then echo "$file"; break; fi; done < <(find $startdir -maxdepth 1 -type f -printf "%T@:%p\n"|sort -nr|cut -d: -f2-))

Here is a Bash script version that is easier to read:

#!/bin/bash
while read file
do
    grep pattern "$file" > /dev/null
    if [[ $? ]]
    then
        echo "$file"
        break
    fi
done < <(find $startdir -maxdepth 1 -type f -printf "%T@:%p\n" |
            sort -nr |
            cut -d: -f2-)

Best Answer

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Grep command to search for a pattern in multiple files and list the files ordering by date

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