从MAC地址中删除前导零

Question

I have a MAC address that looks like this.

01:AA:BB:0C:D0:E1

I want to convert it to lowercase and strip the leading zeros.

1:aa:bb:c:d0:e1

What's the simplest way to do that in a Bash script?

Answer 1

$ echo 01:AA:BB:0C:D0:E1 | sed 's/\(^\|:\)0/\1/g;s/.*/\L\0/'
1:aa:bb:c:d0:e1

\\(^\\|:\\)0 represents either the line start ( ^ ) or a : , followed by a 0. We want to replace this by the capture (either line start or : ), which removed the 0 .

Then, a second substitution ( s/.*/\\L\\0/ ) put the whole line in lowercase.

$ sed --version | head -1
sed (GNU sed) 4.2.2

EDIT: Alternatively:

echo 01:AA:BB:0C:D0:E1 | sed 's/0\([0-9A-Fa-f]\)/\1/g;s/.*/\L\0/'

This replaces 0x (with x any hexa digit) by x .

EDIT: if your sed does not support \\L , use tr :

echo 01:AA:BB:0C:D0:E1 | sed 's/0\([0-9A-Fa-f]\)/\1/g' | tr '[:upper:]' '[:lower:]'

Answer 2

Here's a pure Bash≥4 possibility:

mac=01:AA:BB:0C:D0:E1
IFS=: read -r -d '' -a macary < <(printf '%s:\0' "$mac")
macary=( "${macary[@]#0}" )
macary=( "${macary[@],,}" )
IFS=: eval 'newmac="${macary[*]}"'

• The line IFS=: read -r -d '' -a macary < <(printf '%s:\\0' "$mac") is the canonical way to split a string into an array,
• the expansion "${macary[@]#0}" is that of the array macary with leading 0 (if any) removed,
• the expansion "${macary[@],,}" is that of the array macary in lowercase,
• IFS=: eval 'newmac="${macary[*]}"' is a standard way to join the fields of an array (note that the use of eval is perfectly safe).

After that:

declare -p newmac

yields

declare -- newmac="1:aa:bb:c:d0:e1"

as required.

Answer 3

A more robust way is to validate the MAC address first:

mac=01:AA:BB:0C:D0:E1

a='([[:xdigit:]]{2})'  ;  regex="^$a:$a:$a:$a:$a:$a$"
[[ $mac =~ $regex ]] || { echo "Invalid MAC address" >&2; exit 1; }

And then, using the valid result of the regex match (BASH_REMATCH):

set -- $(printf '%x ' $(printf '0x%s ' "${BASH_REMATCH[@]:1}" ))
IFS=: eval 'printf "%s\n" "$*"'

Which will print:

1:aa:bb:c:d0:e1

Hex values without leading zeros and in lowercase.
If Uppercase is needed, change the printf '%x ' to printf '%X ' .
If Leading zeros are needed change the same to printf '%02x ' .