Mask output card number with ****-CodePudding

So I have a task to mask the first 12 digits of each credit card number with an asterisk (*) given an input file and print the masked number to an output file!

Example card numbers:

1111-2222-3333-4444
4444-3333-2222-1111
1234-5678-9101-1171
1234 5678 9101 1121
7347_9834_7598_2834
8973#9858#3475#8734
2356`7843`0527`5340
8734=7583=4895=7007
8763 2430 6257_9406

Everything should be done in a shell script

My solution is:

#!/bin/bash

file='cards.txt'
while read data; do
echo $data | sed -r 's/[[:digit:]]{4}/****/;s/[[:digit:]]{4}/****/;s/[[:digit:]]{4}/****/;s/[^0-9,*] / /g'
done < $file > cards-masked.txt

Any better ideas on how to use sed in this task?

CodePudding user response：

It is much simple:

cat cards.txt|rev|sed -e 's/[[:digit:]]/*/5g' |rev > cards-masked.txt

echo "1234-5678-9123-1234"|rev|sed -e 's/[[:digit:]]/*/5g' |rev
****-****-****-1234

This one is reverse task:

cat cards.txt|sed -e 's/[[:digit:]]/*/13g' > cards-masked.txt

As you can see there is no need in while/read loop too. Each one sed expression will be evaluated per-line.

CodePudding user response：

This might work for you (GNU sed):

sed -E '/([0-9]{4}[ #`= -_]){3}[0-9]{4}/{s//\n&\n/;h
       s/[0-9]/*/g;G;s/.*\n(.*)\n.*\n(.*)\n.*\n/\2\1/}' file

Surround a match by newlines.

Make a copy.

Replace all digits by *'s

Append the copy.

Using pattern matching, replace the original match by the amended match.

Can be extended for multiple matches on a line:

sed -E ':a;/([0-9]{4}[ #`= -_]){3}[0-9]{4}/{s//\n&\n/;h
       s/[0-9]/*/g;G;s/.*\n(.*)\n.*\n(.*)\n.*\n/\2\1/;ta}' file

To replace only the first nine digits, use:

sed -E ':a;/(([0-9]{4}[ #`= -_]){3})([0-9]{4})/{s//\n\1\n\3/;h
       s/[0-9]/*/g;G;s/.*\n(.*)\n.*\n(.*)\n.*\n/\2\1/;ta}' file

CodePudding user response：

1st solution: Using simple sed perform substitution 3 times of 4 digits to 4 * each time and you are all set.

sed -E 's/[[:digit:]]{4}/****/;s/[[:digit:]]{4}/****/;s/[[:digit:]]{4}/****/' Input_file

2nd solution: With awk program it could be simply done by using 3 times sub(substitute) function.

awk '{sub(/[[:digit:]]{4}/,"****");sub(/[[:digit:]]{4}/,"****");sub(/[[:digit:]]{4}/,"****")} 1' Input_file