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32 .Nd change standard streams initial buffering
41 is used to change the initial buffering of standard input,
42 standard output and/or standard error streams for
46 which is loaded and configured by
48 through environment variables.
50 The options are as follows:
53 Set initial buffering of the standard error stream for
57 .Pq see Sx BUFFER DEFINITION .
59 Set initial buffering of the standard input stream for
63 .Pq see Sx BUFFER DEFINITION .
65 Set initial buffering of the standard output stream for
69 .Pq see Sx BUFFER DEFINITION .
72 Buffer definition is the same as in
74 .Bl -tag -width size -offset indent
80 fully buffered with the default buffer size
82 fully buffered with a buffer of
84 bytes (suffixes 'k', 'M' and 'G' are accepted)
87 In the following example, the stdout stream of the
90 will be fully buffered by default because it does not refer
93 is used to force it to be line-buffered so
95 output will not stall until the full buffer fills.
96 .Bd -literal -offset indent
97 # vmstat 1 | stdbuf -o L awk '$2 > 1 || $3 > 1' | cat -n
105 utility first appeared in
109 The original idea of the
113 who implemented it in the GNU coreutils.