Print SHA sums without "-" at the end?
Solution 1
This is not possible without another tool or without editing the actual sha1sum script/binary. When sha1sum is fed a file it prints the filename after the sum. When sha1sum is not fed a file or is used with a pipe. It puts the - there as a placeholder to indicate that the input was not a file.
Solution 2
Since sha1sum hashes are 40 characters long, you could pipe the output into a head command and pull the first 40 characters from it:
echo test | sha1sum | head -c 40
Source: https://stackoverflow.com/a/14992739/4642023
Solution 3
in bash, no extra tools.
h=($(echo test | sha1sum )) ;echo $h
4e1243bd22c66e76c2ba9eddc1f91394e57f9f83
or
h=( `echo test | sha1sum` ) ;echo $h
In bash this uses the "Array" declaration of h creating an multiindex array of tokens. referencing the variable again with as $h an index array is the same as ${h[0]}
using basic shell substitution
h=`echo test | sha1sum` ;echo ${h// */}
or posix shell (sh, dash, bash) to drop a suffix with %
h=`echo test | sha1sum` ;echo ${h%-}
may also succeed though using the arrays is imho a more intuitive choice.
adding base64
xxd + base64 can be used to increase the entropy (reduce the number of bits) in printable character ranges
h=($(echo test | sha1sum )) ;echo $h|xxd -r -p |base64
ThJDvSLGbnbCup7dwfkTlOV/n4M=
Solution 4
Newline
Understand that the echo is adding a newline at the end which changes the hash:
$ echo test | sha1sum
4e1243bd22c66e76c2ba9eddc1f91394e57f9f83 -
$ echo -n test | sha1sum
a94a8fe5ccb19ba61c4c0873d391e987982fbbd3 -
Answer
But no, there is no way to make sha1sum to print only the hash. The reason is that the line is actually an encoded string. The line could start with a \
and the second space (yes, there are two) between the hash and the filename could become a *
to indicate a binary
hash (useful in DOS):
$ echo "hello" >'a\file'
$ md5sum -b 'a\file'
\b1946ac92492d2347c6235b4d2611184 *a\\file
So, no, it is not a good idea to try to parse that output without understanding the above.
Alternatives
A couple of simpler solutions on other languages are:
$ echo "test" | perl -le 'use Digest::SHA qw(sha1_hex); print sha1_hex(<>);'
4e1243bd22c66e76c2ba9eddc1f91394e57f9f83
Or (for longer input, less memory used), write to a file (lets call it sha1.perl
):
use Digest::SHA qw(sha1_hex);
$state = Digest::SHA->new(sha1);
for (<>) { $state->add($_) }
print $state->hexdigest, "\n";
Execute it:
$ echo "test" | perl sha1.perl
4e1243bd22c66e76c2ba9eddc1f91394e57f9f83
$ echo "test" | php -r '$f = fgets(STDIN); echo sha1($f),"\n";'
4e1243bd22c66e76c2ba9eddc1f91394e57f9f83
Write this to a file (lets call it sha1.py
):
import hashlib
m = hashlib.sha1()
import sys
for line in sys.stdin:
m.update(line)
print m.hexdigest()
Use it:
$ echo "test" | python sha1.py
4e1243bd22c66e76c2ba9eddc1f91394e57f9f83
Solution 5
Seems odd nobody mentioned this, but I find it easiest to just trim the output using "tr" command. Nothing against bash/perl/python regex, but I could never get them all without googling for 5 minutes.
$ echo -n "hello" | sha256sum | tr -d "\n *-"
2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824
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user325067
Updated on September 18, 2022Comments
-
user325067 almost 2 years
Is it possible to have SHA sums print without the
-
appended to the end?$ echo test | sha1sum 4e1243bd22c66e76c2ba9eddc1f91394e57f9f83 - <--- this "-" dash/hyphen
I know we can use
awk
and other command line tools, but can it be done without using another tool?$ echo test | sha1sum | awk '{print $1}' 4e1243bd22c66e76c2ba9eddc1f91394e57f9f83
-
krs013 about 3 yearsAlternatively, you can cut at the space with
echo test | sha1sum | cut -f 1 -d " "
. Same result, but you don't have to count characters.