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Full Discussion: Parsing Output of a Variable
Top Forums Shell Programming and Scripting Parsing Output of a Variable Post 302637109 by bakunin on Tuesday 8th of May 2012 11:03:15 AM
Old 05-08-2012
Quote:
Originally Posted by SkySmart
My question is, how do i "disentangle" these lines, and have them return to the type of line-by-line output one would get with a tail -10?
Code:
VARA="$(tail -10 /var/log/arm.log)"

Notice the double quotes around the subshell, which prevent the shell from evaluating the variables content and the missing "echo", which would do the same, eating away the newlines.

If i may suggest something you didn't ask: don't mix subshell commands "$(...)" and backticks "``". In fact don't use backticks at all! They are only supported for historical purposes and there is no reason at all why one should use them. It is perfectly possible to nest subshells:

Code:
VARA="$(echo $(tail -10 /var/log/arm.log))"

but in your case you better skip the echo altogether and use the version stated above.

I hope this helps.

bakunin
This User Gave Thanks to bakunin For This Post:
 

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LOGTOP(1)						      General Commands Manual							 LOGTOP(1)

NAME
logtop - Realtime log line rate analyser SYNOPSIS
logtop [OPTIONS] DESCRIPTION
logtop is a System Administrator tool analyzing line rate on stdin. It reads on stdin and print a constantly updated result displaying, in columns: Line number, count, frequency, and the actual line. $ tail -f FILE | logtop is the friendly version of: $ watch 'tail FILE | sort | uniq -c | sort -gr' OPTIONS
-s, --size=K Only keep K lines in memory, instead of 10000. -q, --quiet Do not display a live view of the data, only display a top at exit. -l, --line-by-line=K Print result line by line, in a machine friendly format, K is the number of result to print per line. Line by line format is : [%d %f %s ]* %d : Number of occurences %f : Frequency of apparition %s : String (Control chars replaced by dots. -i, --interval=K Interval between graphical updates, in seconds. Defaults to 1. -h, --help Show summary of options. -v, --version Show version of program. EXAMPLES
Here are some logtop usage examples. tail -f cache.log | grep -o "HIT|MISS" | logtop Realtime hit / miss ratio on some caching software log file. tail -f access.log | cut -d' ' -f1 | logtop -s 10000 Realtime most querying IPs on your server, as long as log lines in access.log starts with the client IP. tail -f access.log | cut -d' ' -f7 | logtop -s 10000 Realtime most requested web pages in a NCSA like log file. cat auth.log | grep -v "CRON" | grep -o ": .*" | logtop -q -s 100000 Display a one-shot simple analyse of your auth.log. SEE ALSO
watch(1) AUTHOR
logtop was written by Julien Palard. This manual page was written by Julien Palard <julien@palard.fr>, for the Debian project (and may be used by others). April 16, 2011 LOGTOP(1)
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