coreutils: stdbuf invocation
23.5 ‘stdbuf’: Run a command with modified I/O stream buffering
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‘stdbuf’ allows one to modify the buffering operations of the three
standard I/O streams associated with a program. Synopsis:
stdbuf OPTION... COMMAND
COMMAND must start with the name of a program that
1. uses the ISO C ‘FILE’ streams for input/output (note the programs
‘dd’ and ‘cat’ don’t do that),
2. does not adjust the buffering of its standard streams (note the
program ‘tee’ is not in this category).
Any additional ARGs are passed as additional arguments to the
COMMAND.
The program accepts the following options. Also see ⇒Common
options.
‘-i MODE’
‘--input=MODE’
Adjust the standard input stream buffering.
‘-o MODE’
‘--output=MODE’
Adjust the standard output stream buffering.
‘-e MODE’
‘--error=MODE’
Adjust the standard error stream buffering.
The MODE can be specified as follows:
‘L’
Set the stream to line buffered mode. In this mode data is
coalesced until a newline is output or input is read from any
stream attached to a terminal device. This option is invalid with
standard input.
‘0’
Disable buffering of the selected stream. In this mode, data is
output immediately and only the amount of data requested is read
from input. Note the difference in function for input and output.
Disabling buffering for input will not influence the responsiveness
or blocking behavior of the stream input functions. For example
‘fread’ will still block until ‘EOF’ or error, even if the
underlying ‘read’ returns less data than requested.
‘SIZE’
Specify the size of the buffer to use in fully buffered mode. SIZE
may be, or may be an integer optionally followed by, one of the
following multiplicative suffixes:
‘KB’ => 1000 (KiloBytes)
‘K’ => 1024 (KibiBytes)
‘MB’ => 1000*1000 (MegaBytes)
‘M’ => 1024*1024 (MebiBytes)
‘GB’ => 1000*1000*1000 (GigaBytes)
‘G’ => 1024*1024*1024 (GibiBytes)
and so on for ‘T’, ‘P’, ‘E’, ‘Z’, and ‘Y’. Binary prefixes can be
used, too: ‘KiB’=‘K’, ‘MiB’=‘M’, and so on.
‘stdbuf’ is installed only on platforms that use the Executable and
Linkable Format (ELF) and support the ‘constructor’ attribute, so
portable scripts should not rely on its existence.
Exit status:
125 if ‘stdbuf’ itself fails
126 if COMMAND is found but cannot be invoked
127 if COMMAND cannot be found
the exit status of COMMAND otherwise
Info Catalog
coreutils: nohup invocation
coreutils: Modified command invocation
coreutils: timeout invocation