Ubuntu – How to get specific information from two text lines and assemble a filename from that

command linetext processing

I am currently writing a script to archive a couple log files and want them combined in a single archive which is named according to the first and last lines date and time in one of the log files (i.e. access.log).

But for the best of me I can't wrap my head around how to get this information from the lines and assemble it to a file name.

the lines in question are from an apache.log file which i simply could get with head and tail:

Example:

$ head -n1 /home/server/log/access.log.1 
84.1.11.243 - - [21/Jan/2017:14:53:49 +0000] "GET /index.php/2016/05/26/tutorial-how-to-install-ubuntu-and-other-debian-based-distributions-via-debootstrap/ HTTP/1.1" 200 18413 "https://www.google.hu/" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36"

$ tail -n1 /home/server/log/access.log.1 
71.3.17.120 - - [20/Dec/2017:16:17:50 +0000] "POST / HTTP/1.1" 200 27639 "-" "Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; LCTE; rv:11.0) like Gecko"

The expected file name result should be including the date and time stamps from those messages.

Example line I would like to use, but can change that according to the answers results:

tar -caf "backup-logfiles-$start-til-$end.tar.gz" access.log error.log ftp.log

Any solution is welcome to extract that values into $start and $end.

Best Answer

Here's a horribly convoluted shell one-liner (using the date format you mentioned in chat):

$ name=$(printf 'backup-logfiles-%s-til-%s' $(date -d "$(head -n1 logfile | grep -oP '\[\K\S+' | sed 's|/| |g; s/:/ /')" +%Y-%m-%d-%H:%M:%S) $(date -d "$(tail -n1 logfile | grep -oP '\[\K\S+' | sed 's|/| |g; s/:/ /')" +%Y-%m-%d-%H:%M:%S))
$ echo $name
logfiles-2017-01-21-14:53:49-til-2017-12-20-16:17:50

To get the start and end variables separately, do:

$ start=$(head -n1 logfile | grep -oP '\[\K\S+' | sed 's|/|-|g; s/:/ /')
$ end=$(tail -n1 logfile | grep -oP '\[\K\S+' | sed 's|/|-|g; s/:/ /')
$ echo "backup-logfiles-$start-til-$end.tar.gz"
backup-logfiles-21-Jan-2017 14:53:49-til-20-Dec-2017 16:17:50.tar.gz

Or, if you want a numerical date:

$ start=$(date -d "$(head -n1 logfile | grep -oP '\[\K\S+' | sed 's|/|-|g; s/:/ /')" +%Y-%m-%d-%H:%M:%S)
$ end=$(date -d "$(tail -n1 logfile | grep -oP '\[\K\S+' | sed 's|/|-|g; s/:/ /')" +%Y-%m-%d-%H:%M:%S)
$ echo "backup-logfiles-$start-til-$end.tar.gz"
backup-logfiles-2017-01-21-14:53:49-til-2017-12-20-16:17:50.tar.gz
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