parse md5 in bash

[michael12345]

I'm working on a script and need to parse the hash from a file create by this command:
md5sum somefile >> md5_log

The reason I need to hash is the contents of md5_log does not identify the correct file...sorta.
i.e.

hashnumbers /dev/sda

where /dev/sda is the original file hashed.

I need to compare the hash to the file after it's been moved, thus /dev/sda is incorrect, so md5sum -c will not compare the correct file.

Any input on how I can do this? Parse to white space or copy the hash and replace /dev/sda?
I need a new log file for the comparison.

awk '{print $1}' md5log would seem to have promise if I could concatenate my variable that states the new file to the end of the awk output

finding some good info in here : http://forums.fedoraforum.org/showthread.php?t=220435 but any input is always appreciated.

[daverj]

provide some sample output. Its much easier to hack a script if we know what your expected output looks like.

[michael12345]

#md5sum /dev/sdb >> /folder/md5sum_file

# cat md5sum_file
80c77138c2f5df8eea2cdbd7832c8bdb /dev/sdb

dd if=/dev/sdb of=/folder/copied_drive.dd

Trying to automate the comparison of copied_drive.dd to md5sum_file

md5sum -c md5sum_file will read /dev/sdb and try to scan that device when I want it to actually scan copied_drive.dd5

[michael12345]

got it I think. Thanks. I'll post an update if it's certain.

[cazo]

md5sum's -c option works if you use the relative path of the filename(s) instead of the absolute path. I use this same method to verify files burned to CD/DVD before deleting them.

For example, if the files are in

~/Download/

I first

pushd ~/Download

(or 'cd ~/Download' will work), then

md5sum source/* >> source.md5

. After burning 'source' to the CD/DVD, I use

pushd /media/CD001
md5sum -c ~/Download/source.md5

This will print 'OK' for each file found & verified. Missing and/or changed files will report an error.

I normally use 'pushd' and 'popd' in scripts (as well as the shell) instead of 'cd', since it saves the previous directories on the 'dir stack' and makes getting back easier (for me). Also, the variable $OLDPWD is handy (refers to the previous directory).