How to check if a file is empty in Bash?

Question

I have a file called diff.txt. I Want to check whether it is empty.

I wrote a bash script something like below, but I couldn\'t get it work.

Answer 1

Easiest way for checking file is empty or not:

if [ -s /path-to-file/filename.txt ]
then
     echo "File is not empty"
else
     echo "File is empty"
fi

You can also write it on single line:

[ -s /path-to-file/filename.txt ] && echo "File is not empty" || echo "File is empty"

Answer 2

I came here looking for how to delete empty __init__.py files as they are implicit in Python 3.3+ and ended up using:

find -depth '(' -type f  -name __init__.py ')' -print0 |
  while IFS= read -d '' -r file; do if [[ ! -s $file ]]; then rm $file; fi; done

Also (at least in zsh) using $path as the variable also breaks your $PATH env and so it'll break your open shell. Anyway, thought I'd share!

Answer 3

Misspellings are irritating, aren't they? Check your spelling of empty, but then also try this:

#!/bin/bash -e

if [ -s diff.txt ]
then
        rm -f empty.txt
        touch full.txt
else
        rm -f full.txt
        touch empty.txt
fi

I like shell scripting a lot, but one disadvantage of it is that the shell cannot help you when you misspell, whereas a compiler like your C++ compiler can help you.

Notice incidentally that I have swapped the roles of empty.txt and full.txt, as @Matthias suggests.

Answer 4

[[ -f filename && ! -s filename ]] && echo "filename exists and is empty"

Answer 5

To check if file is empty or has only white spaces, you can use grep:

if [[ -z $(grep '[^[:space:]]' $filename) ]] ; then
  echo "Empty file" 
  ...
fi

Answer 6

[[ -s file ]] --> Checks if file has size greater than 0

if [[ -s diff.txt ]]; then echo "file has something"; else echo "file is empty"; fi

If needed, this checks all the *.txt files in the current directory; and reports all the empty file:

for file in *.txt; do if [[ ! -s $file ]]; then echo $file; fi; done