stdbuf

Run a command with modified buffering operations for its standard streams. More information: https://www.gnu.org/software/coreutils/manual/html_node/stdbuf-invocation.html.

• Change stdin buffer size to 512 KiB:

stdbuf --input=512K command

• Change stdout buffer to line-buffered:

stdbuf --output=L command

• Change stderr buffer to unbuffered:

stdbuf --error=0 command