NAME

stdbuf — change standard streams initial buffering

SYNOPSIS

stdbuf

[ -e bufdef][ -i bufdef][ -o bufdef][ command [ ...]]

DESCRIPTION

stdbuf is used to change the initial buffering of standard input, standard output and/or standard error streams for command. It relies on libstdbuf(3) which is loaded and configured by stdbuf through environment variables.

The options are as follows:

-e bufdef

Set initial buffering of the standard error stream for command as defined by bufdef (see BUFFER DEFINITION).

-i bufdef

Set initial buffering of the standard input stream for command as defined by bufdef (see BUFFER DEFINITION).

-o bufdef

Set initial buffering of the standard output stream for command as defined by bufdef (see BUFFER DEFINITION).

BUFFER DEFINITION

Buffer definition is the same as in libstdbuf(3):

“0”

unbuffered

“L”

line buffered

“B”

fully buffered with the default buffer size

size

fully buffered with a buffer of size bytes (suffixes 'k', 'M' and 'G' are accepted)

EXAMPLES

In the following example, the stdout stream of the awk(1) command will be fully buffered by default because it does not refer to a terminal. stdbuf is used to force it to be line-buffered so vmstat(8)'s output will not stall until the full buffer fills.

# vmstat 1 | stdbuf -o L awk '$2 > 1 || $3 > 1' | cat -n

SEE ALSO

libstdbuf(3), setvbuf(3)

HISTORY

The stdbuf utility first appeared in FreeBSD 8.4.

AUTHORS

The original idea of the stdbuf command comes from Padraig Brady who implemented it in the GNU coreutils. Jeremie Le Hen implemented it on FreeBSD.