How to check if a file is empty in Bash? - linux

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

Answer 1

Misspellings are irritating, aren't they? Check your spelling of empty, but then also try this:
#!/bin/bash -e
if [ -s diff.txt ]; then
# The file is not-empty.
rm -f empty.txt
touch full.txt
else
# The file is empty.
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 2

[ -s file.name ] || echo "file is empty"

Answer 3

[ -s file ] # Checks if file has size greater than 0
[ -s diff.txt ] && echo "file has something" || echo "file is empty"
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

Answer 4

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 5

While the other answers are correct, using the "-s" option will also show the file is empty even if the file does not exist.
By adding this additional check "-f" to see if the file exists first, we ensure the result is correct.
if [ -f diff.txt ]
then
if [ -s diff.txt ]
then
rm -f empty.txt
touch full.txt
else
rm -f full.txt
touch empty.txt
fi
else
echo "File diff.txt does not exist"
fi

Answer 6

Easiest way for checking if 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 7

#geedoubleya answer is my favorite.
However, I do prefer this
if [[ -f diff.txt && -s diff.txt ]]
then
rm -f empty.txt
touch full.txt
elif [[ -f diff.txt && ! -s diff.txt ]]
then
rm -f full.txt
touch empty.txt
else
echo "File diff.txt does not exist"
fi

Answer 8

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

Answer 9

Many of the answers are correct but I feel like they could be more complete
/ simplistic etc. for example :
Example 1 : Basic if statement
# BASH4+ example on Linux :
typeset read_file="/tmp/some-file.txt"
if [ ! -s "${read_file}" ] || [ ! -f "${read_file}" ] ;then
echo "Error: file (${read_file}) not found.. "
exit 7
fi
if $read_file is empty or not there stop the show with exit. More than once I have had misread the top answer here to mean the opposite.
Example 2 : As a function
# -- Check if file is missing /or empty --
# Globals: None
# Arguments: file name
# Returns: Bool
# --
is_file_empty_or_missing() {
[[ ! -f "${1}" || ! -s "${1}" ]] && return 0 || return 1
}

Answer 10

Similar to #noam-manos's grep-based answer, I solved this using cat. For me, -s wasn't working because my "empty" file had >0 bytes.
if [[ ! -z $(cat diff.txt) ]] ; then
echo "diff.txt is not empty"
else
echo "diff.txt is empty"
fi

Answer 11

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!