Append wc lines to filename

Question

Title says it all. I've managed to get just the lines with this:

lines=$(wc file.txt | awk {'print $1'});

But I could use an assist appending this to the filename. Bonus points for showing me how to loop this over all the .txt files in the current directory.

Answer 1

find -name '*.txt' -execdir bash -c \
  'mv -v "$0" "${0%.txt}_$(wc -l < "$0").txt"' {} \;

where

• the bash command is executed for each (\;) matched file;
• {} is replaced by the currently processed filename and passed as the first argument ($0) to the script;
• ${0%.txt} deletes shortest match of .txt from back of the string (see the official Bash-scripting guide);
• wc -l < "$0" prints only the number of lines in the file (see answers to this question, for example)

Sample output:

'./file-a.txt' -> 'file-a_5.txt'
'./file with spaces.txt' -> 'file with spaces_8.txt'