www.nico.schottelius.org/blog/find-emails-in-git-log-for-notification.mdwn

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[[!meta title="Find e-mail adresses of people in git log output"]]
## Motivation
Some days ago I've replaced **cronwrapper**, a script to monitor output of
cron scripts with the replacement **cwrap** in local.ch's puppet configuration.
If the script prints on stdout, **cwrap** does not raise an error by default,
which **cronwrapper** did.
To notify every user of the change, I want to send an email to every
ex-**cronwrapper** user.
## Solution
The configuration is stored in a subversion repo, which I locally sync using
**git svn**. Thus I can use **git log -p** to see all changes.
A typical line of interest looks like this:
- command => '/usr/local/bin/cronwrapper.sh EMAIL@EXAMPLE.COM "[mob][low][dev03-sth][front] description" /usr/bin/php /some/script',
Thanks to git, grep, sed, awk, there is a pretty simple solution
(not the most beautiful) to this problem. First of all, get all patches:
git log -p
Then find all removal entries of cronwrapper:
grep ^- | grep cronwrapper
But only those containing an e-mail address:
grep '@'
And filter out the e-mail address:
sed 's/.* \(.*@.*\)/\1/' | awk '{ print $1 }'
Replace all quotes and backslash quotes:
sed -e 's/\\"//g' -e 's/"//g' -e "s/'//g"
The problem now is that some e-mail adresses are indeed multiple e-mail adresses
(abc@example.com;def@example.com) and some e-mail adresses are lower, some upper case.
Breaking up the concatenated addresses can be done use awk easily:
awk '{ gsub(";", "\n"); print $0 }'
Transforming all addresses to lower case can be done using the fine utility **tr**:
tr '[A-Z]' '[a-z]'
Filter out all duplicates:
sort | uniq
The result is a list of e-mail addresses. Making them usable for copy & paste
into webmail of exchange needs another filter to convert **\n** to **;**, but
add one **\n** at the end:
awk 'ORS=";" { print $0 } END { ORS="\n"; print "" }'
So in the end, the complete chanin looks like this:
git log -p | grep ^- | grep cronwrapper | \
grep '@' | sed 's/.* \(.*@.*\)/\1/' | awk '{ print $1 }' | \
sed -e 's/\\"//g' -e 's/"//g' -e "s/'//g" | \
tr '[A-Z]' '[a-z]' | \
awk '{ gsub(";", "\n"); print $0 }' | \
sort | uniq | \
awk 'ORS=";" { print $0 } END { ORS="\n"; print "" }'
For me, this is a nice demonstration of the power of shell, unix tools and filtering via pipes.
[[!tag config sysadmin localch unix]]