quietly

Remove noise of command line programs while preserving debuggability.

Motivation

When running command line programs such as builds you want 2 things:

• Minimal output on success
• Extensive debug information on error

Unfortunately many tools do not behave like that and instead spam useless debug information in the absence of an issue to debug.
quietly can mitigate this problem by only printing the output when an error happened.

Usage

quietly command - run command

Effect

The last line that command printed is displayed and replaced whenever it prints another. That way you only see the last line printed. If command succeeds (determined by the error code of command), the last line is removed and no output shown. If command fails, the whole output is printed. quietly returns the same error code that command returns.

Example

CC=clang quietly cmake .. && quietly make

Limitations

• Interactive programs are only partially supported. You can do quietly rm -R folder and if there are read-only files rm will print "rm: remove write-protected regular file 'folder/something'?" and you can enter "y" and it will be passed to rm. However, for programs that print a description and then "Are you sure? [y/n]", such as apt-get, you will only see the last line which means you lose context.
• To be able to conditionally print the output of command, quietly needs to store the output. If command prints gigabytes of text, quietly will store said gigabytes of text. If command spits out more text than you have free RAM, you should not use quietly for that command.