grep -v

Show lines that do NOT match (invert)

grep -v inverts the match and prints lines where the pattern is not found. Use it to filter out noise: cat access.log | grep -v 'healthcheck'

Example

$ cat app.log | grep -v 'INFO' | grep -v 'DEBUG'
(only ERROR and WARN lines remain)

Tip: Type it yourself in the terminal below - reading is not the same as doing.