tee - Online Linux Manual PageSection : 2
Updated : 2022-12-04
Source : Linux man-pages 6.03
NAMEtee − duplicating pipe content
LIBRARYStandard C library (libc, −lc)
SYNOPSIS#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <fcntl.h>ssize_t tee(int fd_in, int fd_out, size_t len, unsigned int flags);
DESCRIPTION tee() duplicates up to len bytes of data from the pipe referred to by the file descriptor fd_in to the pipe referred to by the file descriptor fd_out. It does not consume the data that is duplicated from fd_in; therefore, that data can be copied by a subsequent splice(2). flags is a bit mask that is composed by ORing together zero or more of the following values: SPLICE_F_MOVE Currently has no effect for tee(); see splice(2). SPLICE_F_NONBLOCK Do not block on I/O; see splice(2) for further details. SPLICE_F_MORE Currently has no effect for tee(), but may be implemented in the future; see splice(2). SPLICE_F_GIFT Unused for tee(); see vmsplice(2).
RETURN VALUEUpon successful completion, 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 fd_in. On error, tee() returns −1 and errno is set to indicate the error.
ERRORSEAGAIN SPLICE_F_NONBLOCK was specified in flags or one of the file descriptors had been marked as nonblocking (O_NONBLOCK), and the operation would block. EINVAL fd_in or fd_out does not refer to a pipe; or fd_in and fd_out refer to the same pipe. ENOMEM Out of memory.
VERSIONSThe tee() system call first appeared in Linux 2.6.17; library support was added in glibc 2.5.
STANDARDSThis system call is Linux-specific.
NOTESConceptually, tee() copies the data between the two pipes. In reality no real data copying takes place though: under the covers, tee() assigns data to the output by merely grabbing a reference to the input.
EXAMPLESThe example below implements a basic tee(1) program using the tee() system call. Here is an example of its use: $ date | ./a.out out.log | cat
Tue Oct 28 10:06:00 CET 2014
$ cat out.log
Tue Oct 28 10:06:00 CET 2014
Program source #define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int
main(int argc, char *argv[])
{
int fd;
ssize_t len, slen;
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) {
perror("open");
exit(EXIT_FAILURE);
}
for (;;) {
/*
* tee stdin to stdout.
*/
len = tee(STDIN_FILENO, STDOUT_FILENO,
INT_MAX, SPLICE_F_NONBLOCK);
if (len < 0) {
if (errno == EAGAIN)
continue;
perror("tee");
exit(EXIT_FAILURE);
}
if (len == 0)
break;
/*
* Consume stdin by splicing it to a file.
*/
while (len > 0) {
slen = splice(STDIN_FILENO, NULL, fd, NULL,
len, SPLICE_F_MOVE);
if (slen < 0) {
perror("splice");
exit(EXIT_FAILURE);
}
len −= slen;
}
}
close(fd);
exit(EXIT_SUCCESS);
}
SEE ALSOsplice(2), vmsplice(2), pipe(7) 0
Johanes Gumabo
Data Size : 14,864 byte
man-tee.2Build : 2024-12-05, 20:55 :
Visitor Screen : x
Visitor Counter ( page / site ) : 3 / 198,340
Visitor ID : :
Visitor IP : 3.129.216.248 :
Visitor Provider : AMAZON-02 :
Provider Position ( lat x lon ) : 39.962500 x -83.006100 : x
Provider Accuracy Radius ( km ) : 1000 :
Provider City : Columbus :
Provider Province : Ohio , : ,
Provider Country : United States :
Provider Continent : North America :
Visitor Recorder : Version :
Visitor Recorder : Library :
Online Linux Manual Page : Version : Online Linux Manual Page - Fedora.40 - march=x86-64 - mtune=generic - 24.12.05
Online Linux Manual Page : Library : lib_c - 24.10.03 - march=x86-64 - mtune=generic - Fedora.40
Online Linux Manual Page : Library : lib_m - 24.10.03 - march=x86-64 - mtune=generic - Fedora.40
Data Base : Version : Online Linux Manual Page Database - 24.04.13 - march=x86-64 - mtune=generic - fedora-38
Data Base : Library : lib_c - 23.02.07 - march=x86-64 - mtune=generic - fedora.36
Very long time ago, I have the best tutor, Wenzel Svojanovsky . If someone knows the email address of Wenzel Svojanovsky , please send an email to johanes_gumabo@yahoo.co.id .
If error, please print screen and send to johanes_gumabo@yahoo.co.id
Under development. Support me via PayPal.