STDBUF(1) User Commands STDBUF(1)
stdbuf – Run COMMAND, with modified buffering operations for its stan‐
stdbuf OPTION… COMMAND
Run COMMAND, with modified buffering operations for its standard
Mandatory arguments to long options are mandatory for short options
adjust standard input stream buffering
adjust standard output stream buffering
adjust standard error stream buffering
–help display this help and exit
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 follow‐
ing: 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.
tail -f access.log | stdbuf -oL cut -d ‘ ‘ -f1 | uniq
This will immedidately display unique entries from access.log
On GLIBC platforms, specifying a buffer size, i.e., using fully
buffered mode will result in undefined operation.
Written by Padraig Brady.
GNU coreutils online help:
Report stdbuf translation bugs to
Copyright © 2016 Free Software Foundation, Inc. License GPLv3+: GNU
GPL version 3 or later
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Full documentation at:
or available locally via: info ‘(coreutils) stdbuf invocation’
GNU coreutils 8.25 February 2016 STDBUF(1)