I have a C program that continously outputs info to stdout. The problem is that I am redirecting the stdout and stderr to a file and stdout is written at the end of the problem rather than continously to the file. This could be a problem if for example the program is killed and the stdout output is lost. On the other hand, stderr is written continuously to the file.
Thats the way I am doing the redirection of the stdout and stderr.
Any ideas how can I redirect the stdout to the file continuously rather than at the end of the program?
Last edited by methyl; 06-26-2012 at 06:40 PM..
Reason: please use code tags
In bash, I need to send the STDOUT and STDERR from a command to one file, and then just STDERR to another file. Doing one or the other using redirects is easy, but trying to do both at once is a bit tricky. Anyone have any ideas? (9 Replies)
Friends
I have to redirect STDERR messages both to screen and also capture the same in a file.
2 > &1 | tee file works but it also displays the non error messages to file, while i only need error messages.
Can anyone help?? (10 Replies)
Is there a way to redirect all stdout to a file implicitly - like defining stdout=/home/me/process.log - so that all "echo" commands in several scripts/subscripts are written to that file; instead of having to edit all scripts to redirect the "echo" (e.g. echo 'This is a test ' >>... (1 Reply)
I have an executable that, depending on its input, outputs to either one file or several. It usually prints nothing on screen. The usual way to call this program is to specify an input and output filenames, like this:
./executable.exe -i inputfile -o outputfileIt will then try to use the output... (1 Reply)
Hi everybody,
I am trying to do the thing you see in the title, and I can't simply do
a=$(svn up)
echo $a
because the program (svn) gives output on lots of lines and in the variable the output is stored on only one line (resulting in a horribly formatted text). Any tips?
Thanks,... (2 Replies)
Hello,
I have a script (videostream.sh) which invokes the GStreamer command-line tool gst-launch with all the correct command line parameters. When I invoke this program, I add the '&' character at the end to make it a background task, so that my script can complete and exit, i.e.
gst-launch... (1 Reply)
I have a simple bash script that prints sth every 5 seconds. What I do is the following. I redirect the output of the script to a file, tail the file and see that it works and then from another console I delete the file where the output is redirected to. Even though I have deleted the file, the... (2 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)
I have to redirect STDERR messages both to screen and also capture the same in a file but STDOUT only to the same file.
I have searched in this formum for a solution, but something like
srcipt 3>&1 >&2 2>&3 3>&- | tee errs
doesn't work for me...
Has anyone an idea??? (18 Replies)
Hello,
I'm strugling with some redirecting and all help is apreciated.
The following program is working as expected, but the result of the AT command doesn't go to any file.
Thanks in advance for the help.
#!/bin/bash
modem=/dev/ttyUSB1
file=/root/imsi.txt
# print error to stderr and exit... (4 Replies)
Discussion started by: cleitao
4 Replies
LEARN ABOUT REDHAT
stderr
STDIN(3) BSD Library Functions Manual STDIN(3)NAME
stdin, stdout, stderr -- standard I/O streams
SYNOPSIS
#include <stdio.h>
extern FILE *stdin;
extern FILE *stdout;
extern FILE *stderr;
DESCRIPTION
Under normal circumstances every Unix program has three streams opened for it when it starts up, one for input, one for output, and one for
printing diagnostic or error messages. These are typically attached to the user's terminal (see tty(4)) but might instead refer to files or
other devices, depending on what the parent process chose to set up. (See also the ``Redirection'' section of sh(1) .)
The input stream is referred to as ``standard input''; the output stream is referred to as ``standard output''; and the error stream is
referred to as ``standard error''. These terms are abbreviated to form the symbols used to refer to these files, namely stdin, stdout, and
stderr.
Each of these symbols is a stdio(3) macro of type pointer to FILE, and can be used with functions like fprintf(3) or fread(3).
Since FILEs are a buffering wrapper around Unix file descriptors, the same underlying files may also be accessed using the raw Unix file
interface, that is, the functions like read(2) and lseek(2). The integer file descriptors associated with the streams stdin, stdout, and
stderr are 0, 1, and 2, respectively. The preprocessor symbols STDIN_FILENO, STDOUT_FILENO, and STDERR_FILENO are defined with these values
in <unistd.h>.
Note that mixing use of FILEs and raw file descriptors can produce unexpected results and should generally be avoided. (For the masochistic
among you: POSIX.1, section 8.2.3, describes in detail how this interaction is supposed to work.) A general rule is that file descriptors
are handled in the kernel, while stdio is just a library. This means for example, that after an exec, the child inherits all open file
descriptors, but all old streams have become inaccessible.
Since the symbols stdin, stdout, and stderr are specified to be macros, assigning to them is non-portable. The standard streams can be made
to refer to different files with help of the library function freopen(3), specially introduced to make it possible to reassign stdin, stdout,
and stderr. The standard streams are closed by a call to exit(3) and by normal program termination.
SEE ALSO sh(1), csh(1), open(2), fopen(3), stdio(3)CONSIDERATIONS
The stream stderr is unbuffered. The stream stdout is line-buffered when it points to a terminal. Partial lines will not appear until
fflush(3) or exit(3) is called, or a newline is printed. This can produce unexpected results, especially with debugging output. The buffer-
ing mode of the standard streams (or any other stream) can be changed using the setbuf(3) or setvbuf(3) call. Note that in case stdin is
associated with a terminal, there may also be input buffering in the terminal driver, entirely unrelated to stdio buffering. (Indeed, nor-
mally terminal input is line buffered in the kernel.) This kernel input handling can be modified using calls like tcsetattr(3); see also
stty(1), and termios(3).
CONFORMING TO
The stdin, stdout, and stderr macros conform to ANSI X3.159-1989 (``ANSI C89''), and this standard also stipulates that these three streams
shall be open at program startup.
Linux 2.0 March 24, 1998 Linux 2.0