Only get hash value using md5sum (without filename)

user_439621 0
Viewed 166650

I use md5sum to generate a hash value for a file. But I only need to receive the hash value, not the file name.

md5=`md5sum ${my_iso_file}`
echo ${md5}

Output:

3abb17b66815bc7946cefe727737d295  ./iso/somefile.iso

How can I 'strip' the file name and only retain the value?

md5sum shell bash
17 Answers

By leaning on head:

md5_for_file=`md5sum ${my_iso_file}|head -c 32`
user_14878750

For the sake of completeness, a way with sed using a regular expression and a capture group:

md5=$(md5sum "${my_iso_file}" | sed -r 's:\\*([^ ]*).*:\1:')

The regular expression is capturing everything in a group until a space is reached. To get a capture group working, you need to capture everything in sed.

(More about sed and capture groups here: How can I output only captured groups with sed?)

As delimiter in sed, I use colons because they are not valid in file paths and I don't have to escape the slashes in the filepath.

user_109262930

if you're concerned about screwy filenames :

md5sum < "${file_name}" | awk NF=1   

f244e67ca3e71fff91cdf9b8bd3aa7a5

other messier ways to deal with this :

md5sum "${file_name}" | awk NF=NF OFS= FS=' .*$' 
                     or
                      | awk '_{ exit }++_' RS=' '    

f244e67ca3e71fff91cdf9b8bd3aa7a5

to do it entirely inside awk :

mawk 'BEGIN {
    __ = ARGV[ --ARGC ]
     _ = sprintf("%c",(_+=(_^=_<_)+_)^_+_*++_) 
    RS = FS
    gsub(_,"&\\\\&",__)

    ( _=" md5sum < "((_)(__)_) ) | getline

    print $(_*close(_)) }' "${file_name}"

f244e67ca3e71fff91cdf9b8bd3aa7a5
user_146721140
Related