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I have a little script file called testing.sh where I am asking user to enter his login and password. Then, the password is getting encrypted with md5sum command and the result is stored in a file results.txt in a form login:md5password. However, when I am viewing the results.txt file, I only get login:, the encrypted password isn't concatenated. What am I doing wrong?

Here is the testing.sh file:

#!bin/bash
read -p 'Your login: ' uservar
read -sp 'Your password: ' passvar

var=$passvar|md5sum
echo $uservar:$var > ~/Desktop/results.txt

results.txt file:

login:
Evgeny
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  • By the way, md5sum isn't really meant for encryption. md5sum and similar utilities are hashes, i.e. they're meant to just go one way - get a hash sum out of them and used for verifying if data is correct or not, and not really meant to be "decrypted" (although, there's ways to get original string with weak hashes like md5sum and sha1sum, which was cracked last year). Just FYI – Sergiy Kolodyazhnyy Nov 30 '17 at 08:11

2 Answers2

3

You're doing var assignment in wrong way. 

var=$passvar|md5sum

You're supposed to send "$passvar" to md5sum. It won't go through pipe | by itself, so you either need to use echo, or printf. That will output things to stdout stream. You can capture that into variable with command substitution $(...). In other words, you should be doing:

var=$( echo "$passvar" | md5sum )

Also, please remember to quote the variables to preserve the integrity of data stored in them and prevent word splitting.

Other issues:

$ read -sp 'Your password:' passvar
Your password:$ var=$( echo "$passvar" | md5sum )
$ echo "$var"
2b00042f7481c7b056c4b410d28f33cf  -

Notice two things here: there's no newline after "Your password", so you might want to add echo after that command. Second, notice that md5sum outputs filename after the calculated md5 checksum, which in this case is - or stdin stream. You might want to consider getting rid of that part via any text processing utility that will let you cut away words, like awk:

var=$( echo "$passvar" | md5sum | awk '{print $1}')

Alternatively, you can just make use of bash's read and here-string <<< (see this for more info on that operator) :

$ read var trash <<< $( echo "$passvar" | md5sum )
$ echo "$var"
2b00042f7481c7b056c4b410d28f33cf

Last but not least, your #! line is missing / before bin - it should be #!/bin/bash.

The complete script should be as so:

#!/bin/bash
read -p 'Your login: ' uservar
read -sp 'Your password: ' passvar
printf "\n"
read var trash <<< "$(printf "%s" "$passvar" | md5sum)"
printf "%s:%s" "$uservar" "$var" #> ~/results.txt

Note that I commented out redirection to file, just to see the output on the terminal for testing purpose. Here's how it works:

$ ./testing.sh 
Your login: johndoe
Your password: 
johndoe:912ec803b2ce49e4a541068d495ab570$

For future reference, you can add set -x after #!/bin/bash (given that you've properly defined the #! line, of course) to troubleshot the script and see what commands actually run and were errors might arise. Or just use shellcheck online tool.

pa4080
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Sergiy Kolodyazhnyy
  • 105,154
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1

The following script also working for me. 

#!/bin/bash
echo -n 'Your login:'
read uservar

echo -n 'Your password:'
read -s passvar

printf "\n"

encrpt=$(echo "$passvar" | md5sum | awk '{print $1;}')

echo "$uservar":"$encrpt" > /home/bond/result.txt

Output

bond@hp-pc:~$ ./test.sh 
Your login:bond
Your password:
bond@hp-pc:~$ cat result.txt 
bond:22c291f0335f869c154d8081854d9119
Rooney
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