intro.1, _exit.2, access.2, alarm.2, alloc_hugepages.2, arch_prctl.2, bind.2, chdir...

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

diff --git a/man2/tee.2 b/man2/tee.2
index 3a793ce469282078a369d062eab77b4aad46db55..7ede3211e58ca3319296945bc8fe4a1db8f473ea 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@gmx.net>
+.\" 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.
@@ -11,7 +10,7 @@
 .\" manual under the conditions for verbatim copying, provided that the
 .\" entire resulting derived work is distributed under the terms of a
 .\" permission notice identical to this one.
-.\" 
+.\"
 .\" Since the Linux kernel and libraries are constantly changing, this
 .\" manual page may be incorrect or out-of-date.  The author(s) assume no
 .\" responsibility for errors or omissions, or for damages resulting from
@@ -19,27 +18,29 @@
 .\" have taken the same level of care in the production of this manual,
 .\" which is licensed free of charge, as they might when working
 .\" professionally.
-.\" 
+.\"
 .\" 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 2.6.17" "Linux Programmer's Manual"
+.TH TEE 2 2012-05-04 "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 \
+.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
 .\"
 .\"
-.\" add a "tee(in, out1, out2)" system call that duplicates the pages 
-.\" (again, incrementing their reference count, not copying the data) from 
+.\" add a "tee(in, out1, out2)" system call that duplicates the pages
+.\" (again, incrementing their reference count, not copying the data) from
 .\" one pipe to two other pipes.
 .BR tee ()
 duplicates up to
@@ -49,8 +50,8 @@ bytes of data from the pipe referred to by the file descriptor
 to the pipe referred to by the file descriptor
 .IR fd_out .
 It does not consume the data that is duplicated from
-.IR fd_in ; 
-therefore, that data can be copied by a subsequent 
+.IR fd_in ;
+therefore, that data can be copied by a subsequent
 .BR splice (2).
 
 .I flags
@@ -60,18 +61,18 @@ and
 .BR vmsplice (2):
 .TP 1.9i
 .B SPLICE_F_MOVE
-Currently has no effect for 
+Currently has no effect for
 .BR tee ();
 see
 .BR splice (2).
 .TP
 .B SPLICE_F_NONBLOCK
-Do not block on I/O; see 
-.BR splice (2) 
+Do not block on I/O; see
+.BR splice (2)
 for further details.
 .TP
 .B SPLICE_F_MORE
-Currently has no effect for 
+Currently has no effect for
 .BR tee (),
 but may be implemented in the future; see
 .BR splice (2).
@@ -85,19 +86,19 @@ see
 Upon successful completion,
 .BR tee ()
 returns the number of bytes that were duplicated between the input
-and output. 
-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 
+and output.
+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 .
 
-On error, 
+On error,
 .BR tee ()
 returns \-1 and
 .I errno
 is set to indicate the error.
 .SH ERRORS
-.TP 
+.TP
 .B EINVAL
 .I fd_in
 or
@@ -110,6 +111,13 @@ refer to the same pipe.
 .TP
 .B ENOMEM
 Out of memory.
+.SH VERSIONS
+The
+.BR tee ()
+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 ()
@@ -117,14 +125,14 @@ 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 in the output by merely grabbing
 a reference to the input.
 .SH EXAMPLE
 The following example implements a basic
 .BR tee (1)
 program using the
-.BR tee (2)
-system call. 
+.BR tee ()
+system call.
 .nf
 
 #define _GNU_SOURCE
@@ -132,7 +140,6 @@ system call.
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
-#include <assert.h>
 #include <errno.h>
 #include <limits.h>
 
@@ -142,10 +149,13 @@ main(int argc, char *argv[])
     int fd;
     int len, slen;
 
-    assert(argc == 2);
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <file>\\n", argv[0]);
+        exit(EXIT_FAILURE);
+    }
 
     fd = open(argv[1], O_WRONLY | O_CREAT | O_TRUNC, 0644);
-    if (fd == -1) {
+    if (fd == \-1) {
         perror("open");
         exit(EXIT_FAILURE);
     }
@@ -176,7 +186,7 @@ main(int argc, char *argv[])
                 perror("splice");
                 break;
             }
-            len -= slen;
+            len \-= slen;
         }
     } while (1);
 
@@ -184,13 +194,6 @@ main(int argc, char *argv[])
     exit(EXIT_SUCCESS);
 }
 .fi
-.SH HISTORY
-The
-.BR tee (2)
-system call first appeared in Linux-2.6.17.
-.SH "CONFORMING TO"
-This system call is Linux specific.
 .SH SEE ALSO
 .BR splice (2),
-.BR vmsplice (2),
-.BR feature_test_macros (7)
+.BR vmsplice (2)