Bdtyktl

I have a passwd file with the line containing root being:

root:6UZSjeWUui3JQ:0:0:root:/root:/bin/sh

I want this line to be changed to:

root:$1$dog$cNv/OuAd7CMNdrhWsHXAR.:0:0:root:/root:/bin/sh

This password generated using:

hash=$(openssl passwd -1 -salt $salt angus)

which has an embedded / character. So this means I cannot use this sed:

sed -e "s/root:.*:0:0:/root:$hash:0:0:/" './test/etc/passwd'

I have to change to:

sed -e "s|root:.*:0:0:|root:$hash:0:0:|" './test/etc/passwd'

otherwise I get this cryptic error:

sed -e expression #1, char 32: unknown option to `s'

But what if the hash generated has an embedded | character? How would I make this script robust to handle any hash?

Here is my script at present which will fail if a hash has an embedded | character.

eg if call like this:

sudo ./justsed.sh angus dog

Script:

#!/bin/bash



if [[ ! $1 || ! $2 ]]; then

    echo "Usage: justsed.sh <password> <salt>"

    exit 0

fi



# change salt to random chars for real use

salt=$2



# example: $1$dog$cNv/OuAd7CMNdrhWsHXAR.

hash=$(openssl passwd -1 -salt $salt $1)



printf "using the following hash: %s, updating file: %sn" $hash "./test/etc/passwd"



echo "sed command with escaped /"

# this line works

sed -e 's/root:.*:0:0:/root:$1$dog$cNv/OuAd7CMNdrhWsHXAR.:0:0:/' './test/etc/passwd'



echo "sed replace text"

sed -e "s|root:.*:0:0:|root:$hash:0:0:|" './test/etc/passwd'

Just escape it before calling sed:

hash=$(openssl passwd -1 -salt $salt $1 | sed 's|/|\/|g')

sed -e "s|root:.*:0:0:|root:$hash:0:0:|" './test/etc/passwd'

But that will break if your hash contains ", or , as well as if it contains & since sed will read that as "whatever was matched" when the & is present on the right hand side of the substitution operator. So you'll need to escape those as well:

hash=$(openssl passwd -1 -salt $salt $1 | sed -E 's|(["/@])|\1|g')

sed -e "s|root:.*:0:0:|root:$hash:0:0:|" './test/etc/passwd'

Finally, if your hash contains : that will break the whole thing since that can't be escaped given that it's a separator in the passwd file. So I would add a test for that:

if [[ "$hash" =~ /:/ ]];

then

    echo "Invalid password! Choose another"

    exit

fi