Hello. I have one file that is a collection of discarded emails. Each email is it's own section with each section beginning with the same header (ie 'Another Email' ). I want to traverse through the file and every time I find the header ('Another Email') I then want to pick out the 'To:' line... (5 Replies)
Hello,
Our group is just starting to get into UNIX here. We are former REXX users on a VM Mainframe. Can someone point me to the documentation to read a file and write a file in a Unix Shell Script or does this have to be done in another language?
Thank you in advance...
Dave (3 Replies)
I need to write value of variable $version at a particular line in a text file.
Line number is determined by another variable &line......I don't know how to do it in shell script ... (2 Replies)
Hey Guys,
I was wondering if someone would give me a hand with an issue I'm having, let me explain the situation:
I have a file that is constantly being written to and read from with updated lines:
# cat activity.file
activity1
activity2
activity3
activity4
activity5
This file... (2 Replies)
I am trying to write .pgm images using the O_DIRECT flag in open().
I have a char* buffer which has the image data.
I know that I have to align the buffers and have done that using posix_memalign() yet only a part of the image gets written.
Has someone used O_DIRECT for writing files... (3 Replies)
Hi,
I have two text files. Need to create a third text file extracting specific data from first two existing files..
Text File 1: Format contains:
SQL*Loader: Release 10.2.0.1.0 - Production on Wed Aug 4 21:06:34 2010
some text ............so on...and somwhere text like:
Record 1:... (1 Reply)
Hello:
I have the following code:
----------------------------------
open (OUTPUT_FILE, ">>/usr/users/rovolis/PREPAID/CC/TCG/PP.$cyear$cmonth$cday.txt")||die "$!";
82 open (OUTPUT_FILE2, ">>/usr/users/rovolis/PREPAID/CC/TCG/PR.$cyear$cmonth$cday.txt")||die "$!";
83 # ... (0 Replies)
Hi,
I know the code to write a piece of text to the end of a given text file is
echo $text >> filename.txt
I would like to know how to write a piece of text to a file using shell, but the file name isn't given. I want it to write to whatever text file is currently open. Not to all text files... (2 Replies)
Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted!
1. The problem statement, all variables and given/known data:
Write a template main.c file via shell script to make it easier for yourself later.
The issue here isn't writing... (2 Replies)
Discussion started by: george3isme
2 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)