stdbuf

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

TLDR

Change the standard input buffer size to 512 KiB

>_ stdbuf --input=[512K] [command]
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Change the standard output buffer to line-buffered

>_ stdbuf --output=[L] [command]
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Change the standard error buffer to unbuffered

>_ stdbuf --error=[0] [command]
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SYNOPSIS

stdbuf OPTION ... COMMAND

BUGS

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

REPORTING BUGS

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

COPYRIGHT

Copyright 2019 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.

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. 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

SEE ALSO

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

AUTHOR

Written by Padraig Brady.

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