Tail -f: truncate and search

tail -f LOG_FILE | grep --line-buffered SEARCH_STR | cut -d " " -f 7-
Outputs / monitors the content of the LOG_FILE , which matches the SEARCH_STR. The output is cutted by spaces (as delimiter) starting from column 7 till the end.

By: pjsb
2014-08-07 10:40:45

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    truncate -s 1M file
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  • If you use 'tail -f foo.txt' and it becomes temporarily moved/deleted (ie: log rolls over) then tail will not pick up on the new foo.txt and simply waits with no output. 'tail -F' allows you to follow the file by it's name, rather than a descriptor. If foo.txt disappears, tail will wait until the filename appears again and then continues tailing.

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    recursiverse · 2009-07-23 07:37:11 1
  • Not perfect but working (at least on the project i wrote it ;) ) Specify what you want search in var search, then it grep the folder and show one result at a time. Press enter and then it will show the next result. It can work bad on result in the firsts lines, and it can be improved to allow to come back. But in my case (a large project, i was checking if a value wasn't used withouth is corresponding const and the value is "1000" so there was a lot of result ...) it was perfect ;)

    search="whatyouwant";data=$(grep "$search" * -R --exclude-dir=.svn -B2 -A2);for((i=$(echo "$data" | wc -l);$i>0;i=$(($i-6)) )); do clear;echo "$data"| tail -n $i | head -n 5; read;done
    Juluan · 2011-08-29 18:14:16 1
  • tail() { thbin="/usr/bin/tail"; if [ "${1:0:1}" != "-" ]; then fc=$(($#==0?1:$#)); lpf="$((($LINES - 3 - 2 * $fc) / $fc))"; lpf="$(($lpf<1?2:$lpf))"; [ $fc -eq 1 ] && $thbin -n $lpf "$@" | /usr/bin/fold -w $COLUMNS | $thbin -n $lpf || $thbin -n $lpf "$@"; else $thbin "$@"; fi; unset lpf fc thbin; } This is a function that implements an improved version of tail. It tries to limit the number of lines so that the screen is filled completely. It works with pipes, single and multiple files. If you add different options to tail, they will overwrite the settings from the function. It doesn't work very well when too many files (with wrapped lines) are specified. Its optimised for my three-line prompt. It also works for head. Just s/tail/head/g Don't set 'thbin="tail"', this might lead to a forkbomb.

    tail() { thbin="/usr/bin/tail"; if [ "${1:0:1}" != "-" ]; then fc=$(($#==0?1:$#)); lpf="$((($LINES - 3 - 2 * $fc) / $fc))"; lpf="$(($lpf<1?2:$lpf))"; [ $fc -eq 1 ] && $thbin -n $lpf "$@" | /usr/bin/fold -w $COLUMNS | $thbin -n $lpf || $thbin -n $lpf...
    fpunktk · 2012-03-23 19:00:30 0

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