Hello everybody,
Is there a more elegant way to make dual output (display on standard output and append to a file) while I'm executing a shell script, besides duplicating the echo command for every string?
echo "Message..." > 1
echo "Message..." >> myfile.out
Thank you for your time,... (2 Replies)
hello hackers.
i have a curl process running as cgi directly pushing stdout to the client. but i want to additionally save that stream to a file at the same time.
any directions madly welcome.
thanks in advance (3 Replies)
I am trying to have a script ping all the clients then output it to a file so I know which clients are off then have the next script pull the ones that are online and reboot them.
This is what I am running with right now. If there is something KISS then by all means please let me know.
... (3 Replies)
hi
i m trying to print the permissions for a file in output
echo name
read name
touch name.txt
permission=$((ls -l $name.txt))
echo permission
please suggest where i went wrong? (2 Replies)
Hi All,
I have around 900 Select Sql's which I would like to run in an awk script and print the output of those sql's in an txt file.
Can you anyone pls let me know how do I do it and execute the awk script? Thanks. (4 Replies)
Hello all. I've been lurking here for a year or two and finally decided to post.
I need some assistance with file descriptors, stdout, and redirecting output. I've searched through a number of very helpful threads here (unfortunately I can't link to any of them yet due to my low post count...),... (2 Replies)
Hi Friends,
This is the only solution to my task. So, any help is highly appreciated.
I have a file
cat input1.bed
chr1 100 200 abc
chr1 120 300 def
chr1 145 226 ghi
chr2 567 600 unix
Now, I have another file by name
input2.bed (This file is a binary file not readable by the... (7 Replies)
I have a python script that gives output called test.png. By using the following command I run the script every 2 seconds. What is the easiest way to save the output as follows ( test.png (1st output), tes1.png (second output), tes2.png ....)
Command I i use
while sleep 2; do python... (1 Reply)
Why does this until false; do history | head -5; done
result in a stdout infinite loop, yet until false; do history | head -5 > hist5; done
only writes it once to file hist5? Furthermore, I can hear the hard drive working on the 2nd command until I end the process, but the history | head -5 is... (1 Reply)
Discussion started by: Xubuntu56
1 Replies
LEARN ABOUT LINUX
tee
TEE(2) Linux Programmer's Manual TEE(2)NAME
tee - duplicating pipe content
SYNOPSIS
#define _GNU_SOURCE
#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 series of modifier flags, which share the name space with splice(2) and vmsplice(2):
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 VALUE
Upon 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.
ERRORS
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.
VERSIONS
The tee() system call first appeared in Linux 2.6.17.
CONFORMING TO
This system call is Linux-specific.
NOTES
Conceptually, tee() copies the data between the two pipes. In reality no real data copying takes place though: under the covers, tee()
assigns data in the output by merely grabbing a reference to the input.
EXAMPLE
The following example implements a basic tee(1) program using the tee() system call.
#define _GNU_SOURCE
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <limits.h>
int
main(int argc, char *argv[])
{
int fd;
int len, slen;
if (argc != 2) {
fprintf(stderr, "Usage: %s <file>
", argv[0]);
exit(EXIT_FAILURE);
}
fd = open(argv[1], O_WRONLY | O_CREAT | O_TRUNC, 0644);
if (fd == -1) {
perror("open");
exit(EXIT_FAILURE);
}
do {
/*
* 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);
} else
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");
break;
}
len -= slen;
}
} while (1);
close(fd);
exit(EXIT_SUCCESS);
}
SEE ALSO splice(2), vmsplice(2), feature_test_macros(7)COLOPHON
This page is part of release 3.27 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2009-09-15 TEE(2)