CODEWITHSUNDEEP
filebashshellscriptingline
user1904003
user1904003

Reputation: 43

First line of every file in a new file

How can I get the first line of EVERY file in a directory and save them all in a new file?

#!/bin/bash

rm FIRSTLINE
for file in "$(find $1 -type f)";
do
head -1 $file >> FIRSTLINE
done
cat FIRSTLINE

This is my bash script, but when I do this and I open the file FIRSTLINE, then I see this:

==> 'path of the file' <==
'first line' of the file

and this for all the files in my argument.

Does anybody has some solution?

Upvotes: 1

Views: 3801

Answers (4)

Boris
Boris

Reputation: 1143

for gzip files fo instances:

for file in `ls *.gz`; do gzcat $file | head -n 1; done > toto.txt

Upvotes: 0

Alex Khvatov
Alex Khvatov

Reputation: 1485

$ for file in $(find $1 -type f); do echo ''; 
    echo $file; 
    head -n 4 $file; 
  done

Upvotes: 0

Jonathan Wakely
Jonathan Wakely

Reputation: 171263

The problem is that you've quoted the output of find so it gets treated as a single string, so the for loop only runs once, with a single argument containing all the files. That means you run head -1 file1 file2 file3 file4 ... etc. and when given multiple files head prints the ==> file1 <== headers.

So to fix it, remove the double quotes around the find shell-out, which ensures you run the for loop once for each file, as intended. Also, the semi-colon after the shell-out is unnecessary.

#!/bin/bash

rm FIRSTLINE
for file in $(find $1 -type f)
do
    head -1 $file >> FIRSTLINE
done
cat FIRSTLINE

This has some style issues though, do you really need to write to a file then cat the file to stdout? You could just print the output to stdout:

#!/bin/bash

for file in $(find $1 -type f)
do
    head -1 $file
done

Personally I'd write it like this:

find $1 -type f | xargs -L1 head -1

or if you need the output in the file and printed to stdout:

find $1 -type f | xargs -L1 head -1 | tee FIRSTLINE

Upvotes: 3

Zsolt Botykai
Zsolt Botykai

Reputation: 51603

find . -type f -exec head -1 \{\} \; > YOURFILE

might work for you.

Upvotes: 5

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