How can I calculate an MD5 checksum of a directory?

Question

I need to calculate a summary MD5 checksum for all files of a particular type (*.py for example) placed under a directory and all sub-directories.

What is the best way to do that?

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The proposed solutions are very nice, but this is not exactly what I need. I'm looking for a solution to get a single summary checksum which will uniquely identify the directory as a whole - including content of all its subdirectories.

Answer 1

Create a tar archive file on the fly and pipe that to md5sum:

tar c dir | md5sum

This produces a single MD5 hash value that should be unique to your file and sub-directory setup. No files are created on disk.

Answer 2

find /path/to/dir/ -type f -name "*.py" -exec md5sum {} + | awk '{print $1}' | sort | md5sum

The find command lists all the files that end in .py. The MD5 hash value is computed for each .py file. AWK is used to pick off the MD5 hash values (ignoring the filenames, which may not be unique). The MD5 hash values are sorted. The MD5 hash value of this sorted list is then returned.

I've tested this by copying a test directory:

rsync -a ~/pybin/ ~/pybin2/

I renamed some of the files in ~/pybin2.

The find...md5sum command returns the same output for both directories.

2bcf49a4d19ef9abd284311108d626f1  -

To take into account the file layout (paths), so the checksum changes if a file is renamed or moved, the command can be simplified:

find /path/to/dir/ -type f -name "*.py" -exec md5sum {} + | md5sum

On macOS with md5:

find /path/to/dir/ -type f -name "*.py" -exec md5 {} + | md5

Answer 3

ire_and_curses's suggestion of using tar c <dir> has some issues:

• tar processes directory entries in the order which they are stored in the filesystem, and there is no way to change this order. This effectively can yield completely different results if you have the "same" directory on different places, and I know no way to fix this (tar cannot "sort" its input files in a particular order).
• I usually care about whether groupid and ownerid numbers are the same, not necessarily whether the string representation of group/owner are the same. This is in line with what for example rsync -a --delete does: it synchronizes virtually everything (minus xattrs and acls), but it will sync owner and group based on their ID, not on string representation. So if you synced to a different system that doesn't necessarily have the same users/groups, you should add the --numeric-owner flag to tar
• tar will include the filename of the directory you're checking itself, just something to be aware of.

As long as there is no fix for the first problem (or unless you're sure it does not affect you), I would not use this approach.

The proposed find-based solutions are also no good because they only include files, not directories, which becomes an issue if you the checksumming should keep in mind empty directories.

Finally, most suggested solutions don't sort consistently, because the collation might be different across systems.

This is the solution I came up with:

dir=<mydir>; (find "$dir" -type f -exec md5sum {} +; find "$dir" -type d) | LC_ALL=C sort | md5sum

Notes about this solution:

• The LC_ALL=C is to ensure reliable sorting order across systems
• This doesn't differentiate between a directory "named\nwithanewline" and two directories "named" and "withanewline", but the chance of that occurring seems very unlikely. One usually fixes this with a -print0 flag for find, but since there's other stuff going on here, I can only see solutions that would make the command more complicated than it's worth.

PS: one of my systems uses a limited busybox find which does not support -exec nor -print0 flags, and also it appends '/' to denote directories, while findutils find doesn't seem to, so for this machine I need to run:

dir=<mydir>; (find "$dir" -type f | while read f; do md5sum "$f"; done; find "$dir" -type d | sed 's#/$##') | LC_ALL=C sort | md5sum

Luckily, I have no files/directories with newlines in their names, so this is not an issue on that system.

Answer 4

If you only care about files and not empty directories, this works nicely:

find /path -type f | sort -u | xargs cat | md5sum

Answer 5

A solution which worked best for me:

find "$path" -type f -print0 | sort -z | xargs -r0 md5sum | md5sum

Reason why it worked best for me:

1. handles file names containing spaces
2. Ignores filesystem meta-data
3. Detects if file has been renamed

Issues with other answers:

Filesystem meta-data is not ignored for:

tar c - "$path" | md5sum

Does not handle file names containing spaces nor detects if file has been renamed:

find /path -type f | sort -u | xargs cat | md5sum

Answer 6

For the sake of completeness, there's md5deep(1); it's not directly applicable due to *.py filter requirement but should do fine together with find(1).

Answer 7

If you want one MD5 hash value spanning the whole directory, I would do something like

cat *.py | md5sum

Answer 8

Checksum all files, including both content and their filenames

grep -ar -e . /your/dir | md5sum | cut -c-32

Same as above, but only including *.py files

grep -ar -e . --include="*.py" /your/dir | md5sum | cut -c-32

You can also follow symlinks if you want

grep -aR -e . /your/dir | md5sum | cut -c-32

Other options you could consider using with grep

-s, --no-messages         suppress error messages
-D, --devices=ACTION      how to handle devices, FIFOs and sockets;
-Z, --null                print 0 byte after FILE name
-U, --binary              do not strip CR characters at EOL (MSDOS/Windows)

Answer 9

GNU find

find /path -type f -name "*.py" -exec md5sum "{}" +;

Answer 10

Technically you only need to run ls -lR *.py | md5sum. Unless you are worried about someone modifying the files and touching them back to their original dates and never changing the files' sizes, the output from ls should tell you if the file has changed. My unix-foo is weak so you might need some more command line parameters to get the create time and modification time to print. ls will also tell you if permissions on the files have changed (and I'm sure there are switches to turn that off if you don't care about that).

Answer 11

Using md5deep:

md5deep -r FOLDER | awk '{print $1}' | sort | md5sum

Answer 12

I want to add that if you are trying to do this for files/directories in a Git repository to track if they have changed, then this is the best approach:

git log -1 --format=format:%H --full-diff <file_or_dir_name>

And if it's not a Git directory/repository, then the answer by ire_and_curses is probably the best bet:

tar c <dir_name> | md5sum

However, please note that tar command will change the output hash if you run it in a different OS and stuff. If you want to be immune to that, this is the best approach, even though it doesn't look very elegant on first sight:

find <dir_name> -type f -print0 | sort -z | xargs -0 md5sum | md5sum | awk '{ print $1 }'

Answer 13

I had the same problem so I came up with this script that just lists the MD5 hash values of the files in the directory and if it finds a subdirectory it runs again from there, for this to happen the script has to be able to run through the current directory or from a subdirectory if said argument is passed in $1

#!/bin/bash

if [ -z "$1" ] ; then

# loop in current dir
ls | while read line; do
  ecriv=`pwd`"/"$line
if [ -f $ecriv ] ; then
    md5sum "$ecriv"
elif [ -d $ecriv ] ; then
    sh myScript "$line" # call this script again
fi

done


else # if a directory is specified in argument $1

ls "$1" | while read line; do
  ecriv=`pwd`"/$1/"$line

if [ -f $ecriv ] ; then
    md5sum "$ecriv"

elif [ -d $ecriv ] ; then
    sh myScript "$line"
fi

done


fi

Answer 14

If you want really independence from the file system attributes and from the bit-level differences of some tar versions, you could use cpio:

cpio -i -e theDirname | md5sum

Answer 15

md5sum worked fine for me, but I had issues with sort and sorting file names. So instead I sorted by md5sum result. I also needed to exclude some files in order to create comparable results.

find . -type f -print0 \ | xargs -r0 md5sum \ | grep -v ".env" \ | grep -v "vendor/autoload.php" \ | grep -v "vendor/composer/" \ | sort -d \ | md5sum

Answer 16

There are two more solutions:

Create:

du -csxb /path | md5sum > file

ls -alR -I dev -I run -I sys -I tmp -I proc /path | md5sum > /tmp/file

Check:

du -csxb /path | md5sum -c file

ls -alR -I dev -I run -I sys -I tmp -I proc /path | md5sum -c /tmp/file