sed-style replace letters with random letters, numbers with random numbers - bash

Question

I need to take a large file, with lines such as:
member: cn=user0001,ou=people
And replace all the usernames such that they still have letters in the same position and numbers in the same position, at random. So the output might be something like:
member: cn=kvud7405,ou=people
The usernames vary in length and format, but they're always bounded by a cn= and a comma.
Can anyone offer a solution with sed/awk/bash preferably, or failing that python might be an option (not sure which version).
Thanks in advance.

Answer 1

something like
sed -i 's/blah/blah?$(cat /dev/urandom | tr -dc "a-z0-9" | fold -w 6 | head -n 1)/g' /home/test.html

Answer 2

awk -F 'cn=|,' 'BEGIN {srand(); OFS = ""} {n = split($2, a, ""); for (i = 1; i <= n; i++) {if (a[i] ~ /[[:digit:]]/) {new = new int(rand() * 10)} else {new = new sprintf("%c", int(rand() * 26 + 97))}}; $2 = "cn=" new ","; print}'
Broken out on multiple lines:
awk -F 'cn=|,' '
BEGIN {
srand();
OFS = ""
}
{
n = split($2, a, "");
for (i = 1; i <= n; i++) {
if (a[i] ~ /[[:digit:]]/) {
new = new int(rand() * 10)
}
else {
new = new sprintf("%c", int(rand() * 26 + 97))
}
};
$2 = "cn=" new ",";
print
}'
It could easily be modified to handle uppercase alpha characters if needed.
Edit:
More robust:
awk 'BEGIN {srand()} {match($0, /cn=[^,]*,/); n = split(substr($0, RSTART+3, RLENGTH-4), a, ""); for (i = 1; i <= n; i++) {if (a[i] ~ /[[:digit:]]/) {new = new int(rand() * 10)} else {new = new sprintf("%c", int(rand() * 26 + 97))}}; print substr($0, 1, RSTART+2) new substr($0, RSTART+RLENGTH-1)}'
This version doesn't use FS so it works when there are additional fields.

Answer 3

A Bash solution:
letter=( a b c d e f g h i j k l m n o p q r s t u v w x y z )
digit=( 0 1 2 3 4 5 6 7 8 9 0 )
while read line; do
user=''
line=${line#*=} # separate cn-value
line=${line%,*} # separate cn-value
for (( CNTR=0; CNTR<${#line}; CNTR+=1 )); do
if [[ ${line:CNTR:1} =~ [[:alpha:]] ]] ; then
user=$user${letter[RANDOM%26]}
else
user=$user${digit[RANDOM%10]}
fi
done
echo "member: cn=${user},ou=people"
done < "$infile" > "$tempfile"
mv "$tempfile" "$infile" # replace original file