Cfrtjryk

I use the MAC address of the machine as userid and would like to update a file (display.txt) that will display the userid/expiry. How do I replace the expdate in display.txt with the date in expdate.txt corresponding to the MAC address.

I succeed with the userid part, with:

sed -i "s/user/$(ifconfig eth0 |

                 grep -o -E '([[:xdigit:]]{2}:){5}[[:xdigit:]]{2}')/" 

/user/id/display.txt > /dev/null

display.txt:

UserID: user

User expiring on expdate

expdate.txt:

user                          = 00:09:34:2C:66:AB

expdate                       = 2017-05-20

user                          = 00:09:34:29:86:6C

expdate                       = 2017-08-23

I would like to have:

display.txt:

UserID: 00:09:34:29:86:6C

User expiring on 2017-08-23

I found a one-liner solution using grep and sed:

mac=$(ifconfig eth1 | grep -o -E '([[:xdigit:]]{2}:){5}[[:xdigit:]]{2}'); grep "$mac" expdate.txt -A 1 | sed -r ':a;N;$!ba;s!user.*=.(..:..:..:..:..:..).*expdate.*=.(....-..-..)!UserID: 1nUser expiring on 2!g' > display.txt

and to validate it works with any mac address I tested with:

mac=$(echo "00:09:34:29:86:6C") ; grep "$mac" expdate.txt -A 1 | sed -r ':a;N;$!ba;s!user.*=.(..:..:..:..:..:..).*expdate.*=.(....-..-..)!UserID: 1nUser expiring on 2!g' > display2.txt

I generated the output from scratch, if you need a replacement in an existing file, I suggest to use a templating language like mustache. The Bash version is on GitHub

However because it seems you need to re-use the mac address (for searching first and then for the output) I suggest to make a bash script
and it would be more re-usable.

By concatenating sed outputs:

sed -e 's/user/UserID/g' expdate.txt | sed -e 's/ //g' | sed -e 's/=/: /g' | sed -e 's/expdate:/User expiring on/g' > display.txt

(It's pretty sure that this could be done also with only one sed)