frep is a pretty
special tool, a mix of cut and uniq. I use it to get an overview
of very similar data. For example, given a log file:
% cat log
2013-06-15 foo
2013-06-15 bar
2013-07-16 foo
2013-07-16 bar
2013-07-17 baz
We only want to see one line per day, so we filter consecutive duplicates of the first field (or, rather, we print when the first field changes):
% frep 1 < log
2013-06-15 foo
2013-07-16 foo
2013-07-17 baz
And sometimes we want to see the last line for each duplicate value:
% frep -l 1 < log
2013-06-15 bar
2013-07-16 bar
2013-07-17 baz
Finally, we also can refine the field seperator and for example, only list one line per month:
% frep -F- 1 2 < log
2013-06-15 foo
2013-07-16 foo
Another example would be to list which program uses most CPU, for each user:
% ps -eo pid,user,pcpu,comm --sort user,-pcpu | frep 2
PID USER %CPU COMMAND
3479 chris 2.8 firefox
971 dbus 0.0 dbus-daemon
25256 dovecot 0.0 anvil
973 mpd 0.0 mpd
995 ntp 0.0 ntpd
8724 postfix 0.0 qmgr
2474 root 1.2 X
4040 unbound 0.0 unbound
NP: Cameron Boucher—Life in Vain (Daniel Johnston Cover)