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Unique number by Mac Address

Terminal - Unique number by Mac Address
UNIQUE_BY_MAC=$(ifconfig |grep eth0|awk '{ print strtonum("0x"substr($6,16,2)) }')
2010-06-01 17:34:43
User: rubo77
Functions: awk grep ifconfig
Unique number by Mac Address

gets the last number of the mac address to use it for other stuff


There are 7 alternatives - vote for the best!

Terminal - Alternatives

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What others think

5 not $6. if $6 for you then it means that your command don't work on some distribs according probably to ifconfig version.
Comment by pepin 297 weeks and 3 days ago

Not random at all. It would be more suitable to call it a non-unique hardware ID. Consider using

printf '%x' "$((RANDOM % 256))"


Comment by bugmenot 297 weeks and 2 days ago

What's more I've hot en0 and en1 on a Mac and not eth0.

Comment by bugmenot 297 weeks and 2 days ago


i changed it to $5 and call it unique instead of "random"

Comment by rubo77 277 weeks and 3 days ago

no, if i change it to $5 it doesent work on ubuntu (debian)!

the idea is for example to get the


out of

eth0 Link encap:Ethernet Hardware Adresse 00:12:b7:88:1c:f3

and change that to an integer, which will be


in this case

sure if it doesent work on your system cause the output of ifconfig is diffenren t try with $5:

UNIQUE_BY_MAC=$(ifconfig |grep eth0|awk '{ print strtonum("0x"substr($5,16,2)) }')
Comment by rubo77 277 weeks and 3 days ago

you need


installed to run awk with the strtonum() function:

sudo aptitude install gawk
Comment by rubo77 277 weeks and 3 days ago

Your point of view

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