How to select the first line from each file in a directory and print it into a new text file

I have a directory with several .txt files.

From each of these files, I want to select the first line and print it into a new .txt file (to get a list of all the first lines).

I tried it with the awk and sed commands and combined it with a loop, but without success.

5 Answers

Use head:

head -n1 -q *.txt > new-file 

• -n1 tells head to extract the first line only.
• -q tells head not to print the filename.

On OS X (and probably on some other *nix variants) the -q option is not supported by head. You need to remove the filenames yourself, e.g.

head -n1 *.txt | grep -v '==> ' > new-file 

This only works if you know the output shouldn't contain the ==>  string. To be absolutely sure, use a loop (which will be much slower than running head just once):

for file in *.txt ; do head -n1 "$file" done 

Using grep:

grep -m 1 '.' *.txt >output.file 

grep will match any character and will exit after first match i.e. grep will output the first lines of all the input files and we are saving those in out.txt.

Using only Bash:

for f in *.txt; do <"$f" read line; printf "$line\n" >>new.txt; done 

• *.txt is expanded to the list of folders / files ending with .txt in the current working directory (since there are only files folders ending with .txt are not a concern);
• <"$f" read line reads one line from the file path stored in f and stores it in line;
• printf "$line\n" >>new.txt: appends the content of line to new.txt;

% cat foo.txt line #1 in foo line #2 in foo line #3 in foo % cat bar.txt line #1 in bar line #2 in bar line #3 in bar % for f in *.txt; do <"$f" read line; printf "$line\n" >>new.txt; done % cat new.txt line #1 in bar line #1 in foo 

You have tried it with awk, here is a awk version

awk 'FNR==1 {print} {nextfile}' *.txt > out 

Another approach with AWK is to tell AWK to print, but then immediately go to next file

tmp:$ touch file1 file2 file3 tmp:$ printf "Line 1 \n Line 2" | tee file1 file2 file3 Line 1 Line 2 tmp:$ awk '{print;nextfile}' file1 file2 file3 Line 1 Line 1 Line 1 

sed also allows printing of specific lines . Here I've combined that with find

tmp:$ find . -name "file*" -exec sed -n '1p' {} \; Line 1 Line 1 Line 1 

And perl:

tmp:$ find . -name "file*" -exec perl -ne 'print if 1..1' {} \; Line 1 Line 1 Line 1 

And last but not least , grep

tmp:$ grep -n 1 file1 file2 file3 file1:1:Line 1 file2:1:Line 1 file3:1:Line 1 

Saving everything to a single file is just a matter of appending > outputFile.txt at the end of these commands.