I have a text file:
10 20 30 40
50 60 60 80
By using
$ wc -l file.txt
2 file.txt
I get the count, but I want to add that result in my text file.
I want the result to be like this:
2
10 20 30 40
50 60 70 80
What should I do in order to prepend the result in the text file?
I have many of these files in one folder, and instead of providing a single text file at a time, I want to provide all the files at the same time.
For one file, you can do this:
wc -l < file.txt | cat - file.txt > tmp && mv tmp file.txt
This uses cat to concatenate the result of wc -l < file.txt with the contents of file.txt. The result is written to a temporary file, then the original file is overwritten.
For many files (e.g. all files ending in .txt), you can use a loop:
for file in *.txt; do
wc -l < "$file" | cat - "$file" > tmp && mv tmp "$file"
done
Try:
echo `wc -l myfile.txt` | cat - myfile.txt > tmp && mv tmp myfile.txt
Awk may be your friend :
awk 'BEGIN{RS="^$"}NR=FNR{printf "%d\n%s",gsub(/\n/,"\n"),$0}' file \
> temp && mv temp file
