CODEWITHSUNDEEP
linuxbashsed
Mike Laren
Mike Laren

Reputation: 8188

How to delete the Nth line of a bunch of files

I have a set of 30+ files containing key-value pairs or translated strings in the format:

key=some text

Sometimes I want to delete some keys from these files and what I do is open one of them, locate the line that contains the key I want to delete (e.g. line 310) and then manually delete that line from the other files. Keys in these files are sorted alphabetically, hence if a the key appears on line 310 of a file, then it appears in line 310 of every other file.

What would be an easy way to delete a line by number (e.g. line 310) from a bunch of files?

Upvotes: 1

Views: 210

Answers (2)

Phil Krylov
Phil Krylov

Reputation: 530

sed -i '' '310d' file1 file2 ...

will delete line 310 from all files specified keeping no backup copies. The full procedure as defined by you goes like this:

KEY=mykey
FILE1=myfile
ALL_FILES="file1 file2 ..."
sed -i '' $(grep -n "^$KEY=" $FILE1 | head -1 | sed -E 's/^([0-9]+):.*/\1/')d $ALL_FILES

but a simpler approach is:

KEY=mykey
ALL_FILES="file1 file2 ..."
sed -i '' "/^$KEY=/d" $ALL_FILES

which means "delete every line starting with 'mykey=' from $ALL_FILES keeping no backup copies".

Upvotes: 4

shellter
shellter

Reputation: 37318

Expanding on user000001 idea, here's a more general approach.

    sed -i.bak "$(grep -n keyTarget keyFile|sed 's/:.*$//')d;" files*

Assuming your sed supports the -i option (most do).

You could even put this in a script and so than rather than editing keyTarget each time, you would just use a command-line parameter by use instead of keyTarget , ${@} .

To confirm this will work as you expect, confirm you only get one line number back from the internal part

grep -n keyTarget keyFile|sed 's/:.*$//'

Until you're very certain that you never find a case where line numbers are off, I would save the whole collections of files to a backup dir.

Having the script support editing multiple targets gets risker, but could be done . If you like this and it works for you needs, but you could use multiple targets, post a new question, showing where you are stuck.

IHTH

Upvotes: 1

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