# phpman > man > stdbuf(1)

> **TLDR:** Run a command with modified buffering operations for its standard streams.
>
- Change `stdin` buffer size to 512 KiB:
  `stdbuf {{-i|--input}} 512K {{command}}`
- Change `stdout` buffer to line-buffered:
  `stdbuf {{-o|--output}} L {{command}}`
- Change `stderr` buffer to unbuffered:
  `stdbuf {{-e|--error}} 0 {{command}}`

*Source: tldr-pages*

---

[STDBUF(1)](https://www.chedong.com/phpMan.php/man/STDBUF/1/markdown)                                   User Commands                                  [STDBUF(1)](https://www.chedong.com/phpMan.php/man/STDBUF/1/markdown)



## 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
              adjust standard input stream buffering

### -o --output
              adjust standard output stream buffering

### -e --error
              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.  Binary prefixes can be used, too:
       KiB=K, MiB=M, and so on.  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 any translation bugs to <<https://translationproject.org/team/>>

## COPYRIGHT
       Copyright © 2020 Free Software Foundation, Inc.  License GPLv3+: GNU GPL version 3  or  later
       <<https://gnu.org/licenses/gpl.html>>.
       This  is free software: you are free to change and redistribute it.  There is NO WARRANTY, to
       the extent permitted by law.

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



GNU coreutils 8.32                          January 2026                                   [STDBUF(1)](https://www.chedong.com/phpMan.php/man/STDBUF/1/markdown)