sched_setattr.2: tfix

[thirdparty/man-pages.git] / man2 / tee.2

diff --git a/man2/tee.2 b/man2/tee.2
index 0514b15fbc3a2632a8a65679786224a3d22ad1a8..03d043b4617abb1c7b1a79cb398effec058e8407 100644 (file)
--- a/man2/tee.2
+++ b/man2/tee.2
@@ -1,8 +1,7 @@
-.\" Hey Emacs! This file is -*- nroff -*- source.
-.\"
 .\" This manpage is Copyright (C) 2006 Jens Axboe
 .\" and Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
 .\"
+.\" %%%LICENSE_START(VERBATIM)
 .\" Permission is granted to make and distribute verbatim copies of this
 .\" manual provided the copyright notice and this permission notice are
 .\" preserved on all copies.
@@ -22,18 +21,20 @@
 .\"
 .\" Formatted or processed versions of this manual, if unaccompanied by
 .\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
 .\"
-.TH TEE 2 2006-04-28 "Linux" "Linux Programmer's Manual"
+.TH TEE 2 2019-03-06 "Linux" "Linux Programmer's Manual"
 .SH NAME
 tee \- duplicating pipe content
 .SH SYNOPSIS
 .nf
-.B #define _GNU_SOURCE
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
 .B #include <fcntl.h>
-
-.BI "long tee(int " fd_in ", int " fd_out ", size_t " len \
+.PP
+.BI "ssize_t tee(int " fd_in ", int " fd_out ", size_t " len \
 ", unsigned int " flags );
 .fi
+.\" Return type was long before glibc 2.7
 .SH DESCRIPTION
 .\" Example programs http://brick.kernel.dk/snaps
 .\"
@@ -52,12 +53,10 @@ It does not consume the data that is duplicated from
 .IR fd_in ;
 therefore, that data can be copied by a subsequent
 .BR splice (2).
-
+.PP
 .I flags
-is a series of modifier flags, which share the name space with
-.BR splice (2)
-and
-.BR vmsplice (2):
+is a bit mask that is composed by ORing together
+zero or more of the following values:
 .TP 1.9i
 .B SPLICE_F_MOVE
 Currently has no effect for
@@ -90,7 +89,7 @@ A return value of 0 means that there was no data to transfer,
 and it would not make sense to block, because there are no
 writers connected to the write end of the pipe referred to by
 .IR fd_in .
-
+.PP
 On error,
 .BR tee ()
 returns \-1 and
@@ -98,6 +97,14 @@ returns \-1 and
 is set to indicate the error.
 .SH ERRORS
 .TP
+.B EAGAIN
+.B SPLICE_F_NONBLOCK
+was specified in
+.IR flags
+or one of the file descriptors had been marked as nonblocking
+.RB ( O_NONBLOCK ) ,
+and the operation would block.
+.TP
 .B EINVAL
 .I fd_in
 or
@@ -113,9 +120,10 @@ Out of memory.
 .SH VERSIONS
 The
 .BR tee ()
-system call first appeared in Linux 2.6.17.
-.SH "CONFORMING TO"
-This system call is Linux specific.
+system call first appeared in Linux 2.6.17;
+library support was added to glibc in version 2.5.
+.SH CONFORMING TO
+This system call is Linux-specific.
 .SH NOTES
 Conceptually,
 .BR tee ()
@@ -123,22 +131,32 @@ copies the data between the two pipes.
 In reality no real data copying takes place though:
 under the covers,
 .BR tee ()
-assigns data in the output by merely grabbing
+assigns data to the output by merely grabbing
 a reference to the input.
 .SH EXAMPLE
-The following example implements a basic
+The example below implements a basic
 .BR tee (1)
 program using the
 .BR tee ()
 system call.
-.nf
-
+Here is an example of its use:
+.PP
+.in +4n
+.EX
+$ \fBdate |./a.out out.log | cat\fP
+Tue Oct 28 10:06:00 CET 2014
+$ \fBcat out.log\fP
+Tue Oct 28 10:06:00 CET 2014
+.EE
+.in
+.SS Program source
+\&
+.EX
 #define _GNU_SOURCE
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
-#include <assert.h>
 #include <errno.h>
 #include <limits.h>
 
@@ -148,7 +166,10 @@ main(int argc, char *argv[])
     int fd;
     int len, slen;
 
-    assert(argc == 2);
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <file>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
 
     fd = open(argv[1], O_WRONLY | O_CREAT | O_TRUNC, 0644);
     if (fd == \-1) {
@@ -189,8 +210,8 @@ main(int argc, char *argv[])
     close(fd);
     exit(EXIT_SUCCESS);
 }
-.fi
+.EE
 .SH SEE ALSO
 .BR splice (2),
 .BR vmsplice (2),
-.BR feature_test_macros (7)
+.BR pipe (7)