stdbuf (1)

Quick Reference

Run a command with modified buffering operations for its standard streams.

  • Change the standard input buffer size to 512 KiB:

stderr --input={{512K}} {{command}}

  • Change the standard output buffer to line-buffered:

stdbuf --output={{L}} {{command}}

  • Change the standard error buffer to unbuffered:

stdbuf --error={{0}} {{command}}

NAME

stdbuf - Run COMMAND, with modified buffering operations for its standard streams.

SYNOPSIS

stdbuf OPTION... COMMAND

DESCRIPTION

Run COMMAND, with modified buffering operations for its standard streams.
Mandatory arguments to long options are mandatory for short options too.
-i, --input=MODE
adjust standard input stream buffering
-o, --output=MODE
adjust standard output stream buffering
-e, --error=MODE
adjust standard error stream buffering
--help
display this help and exit
--version
output version information and exit
If MODE is 'L' the corresponding stream will be line buffered. This option is invalid with standard input.
If MODE is '0' the corresponding stream will be unbuffered.
Otherwise MODE is a number which may be followed by one of the following: KB 1000, K 1024, MB 1000*1000, M 1024*1024, and so on for G, T, P, E, Z, Y. In this case the corresponding stream will be fully buffered with the buffer size set to MODE bytes.
NOTE: If COMMAND adjusts the buffering of its standard streams ('tee' does for example) then that will override corresponding changes by 'stdbuf'. Also some filters (like 'dd' and 'cat' etc.) don't use streams for I/O, and are thus unaffected by 'stdbuf' settings.

EXAMPLES

tail -f access.log | stdbuf -oL cut -d ' ' -f1 | uniq
 
This will immediately display unique entries from access.log

BUGS

On GLIBC platforms, specifying a buffer size, i.e., using fully buffered mode will result in undefined operation.

AUTHOR

Written by Padraig Brady.

REPORTING BUGS

GNU coreutils online help: <https://www.gnu.org/software/coreutils/>
 
Report stdbuf translation bugs to <https://translationproject.org/team/>

SEE ALSO

Full documentation at: <https://www.gnu.org/software/coreutils/stdbuf>
 
or available locally via: info '(coreutils) stdbuf invocation'

Information

Source
Coreutils
OS/version
GNU coreutils 8.29.13-0a854
Source updated
December 2, 2018
Page created
February 9, 2018
Page generated
December 2, 2018