Modify continuous output of a command
suggest change~$ ping -c 1 google.com # unmodified output
PING google.com (16.58.209.174) 56(84) bytes of data.
64 bytes from wk-in-f100.1e100.net (16.58.209.174): icmp_seq=1 ttl=53 time=47.4 ms
~$ ping google.com | grep -o '^[0-9]\+[^()]\+' # modified output
64 bytes from wk-in-f100.1e100.net
64 bytes from wk-in-f100.1e100.net
64 bytes from wk-in-f100.1e100.net
64 bytes from wk-in-f100.1e100.net
64 bytes from wk-in-f100.1e100.net
64 bytes from wk-in-f100.1e100.net
64 bytes from wk-in-f100.1e100.net
64 bytes from wk-in-f100.1e100.net
64 bytes from wk-in-f100.1e100.net
64 bytes from wk-in-f100.1e100.net
...
The pipe (|
) connects the stdout
of ping
to the stdin
of grep
, which processes it immediately. Some other commands like sed
default to buffering their stdin
, which means that it has to receive enough data, before it will print anything, potentially causing delays in further processing.
Found a mistake? Have a question or improvement idea?
Let me know.
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