This small script filters long STDIN output, performing several functions to keep track of the important parts and progresses, which will be hard to do with a shell script.

It is useful for filtering the output of verbose Travis-CI commands, but may be useful in other contexts where there is a limit to the amount of kept output.

All arguments are optional:

• --count-step=n: displays COUNT <tab> <step> every n lines.
• --last=n: displays the last n lines prefixed with "LAST\t"
• --filter=<regex pattern>: displays matching lines with a "FOUND\t" prefix.
• --suppress-last-on=<regex>: suppress the last lines if their concatenated output matches the regex.

Examples:

python zenfilter.py --count-step=10 --last=200 --filter="[0-9]+"
python zenfilter.py --last=20
python zenfilter.py --last=25 --count-step=15

A use case scenario:

make 2>&1 | python zenfilter.py [args]