First off I'm not sure what you're trying to do here but to reinforce what has already been stated by spirtle the code needs to be rectified.
There's no need to cast the int read from standard input to char so the char c; c = (char) in; and c = NULL; statements are unneccessary as this one suffices.
The terminal condition for the while loop should check for EOF instead of NULL
and fputc() writes to stdout NOT stdin
Hi,
Program A: uses pipe()
I am able to read the stdout of PROGAM B (stdout got through system() command) into PROGRAM A using:
* child
-> dup2(fd, STDOUT_FILENO);
-> execl("/path/PROGRAM B", "PROGRAM B", NULL);
* parent
-> char line;
-> read(fd, line, 100);
Question:... (2 Replies)
Hi everyone, first post here.
Anyone who isn't interested in the background, press pagedown :).
I sometimes need to make scripts for little things I need in the infrastructure at the company I work at. Currently I am trying to make a wrapper script for a proprietary image-deployment program.... (2 Replies)
Hi,
i know how to
a) redirect stdout and stderr to one file,
b) and write to two files concurrently with same output using tee command
Now, i want to do both the above together.
I have a script and it should write both stdout and stderr in one file and also write the same content to... (8 Replies)
Hi,
I am working on a project where I have to generate and execute nasm code on-the-fly. I generate the code in a file program.asm and then execute it.This output is to stdout which i redirect to an output file which i read back to compare results:
system("nasm -f elf program.asm >... (5 Replies)
All,
Ok...so I know I *should* be able to control a process's stdin and stdout from the parent by creating pipes and then dup'ing them in the child. And, this works with all "normal" programs that I've tried. Unfortunately, I want to intercept the stdin/out of the scp application and it seems... (9 Replies)
Hi,
i am using the below program to read from the standard input or to write to standard out put.
i know that using highlevel functions this can be done better than what i have done here.
i just want to know is there any other method by which i find the exact number of characters ( this... (3 Replies)
I want to differentiate the STDOUT and STDERR messages in my terminal .
If a script or command is printing a message in terminal I want to differentiate by colors,
Is it possible ?
Example:
$date
Wed Jul 27 12:36:50 IST 2011
$datee
bash: datee: command not found
$alias ls
alias... (2 Replies)
Well.. let's say i need to write a pretty simple script.
In my script i have 2 variables which can have value of 0 or 1.
$VERBOSE
$LOG
I need to implement these cases:
($VERBOSE = 0 && $LOG = 0) => ONLY ERROR output (STDERR to console && STDOUT to /dev/null)
($VERBOSE = 1... (5 Replies)
Discussion started by: Marmz
5 Replies
LEARN ABOUT CENTOS
fflush
FFLUSH(3P) POSIX Programmer's Manual FFLUSH(3P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the correspond-
ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
NAME
fflush - flush a stream
SYNOPSIS
#include <stdio.h>
int fflush(FILE *stream);
DESCRIPTION
If stream points to an output stream or an update stream in which the most recent operation was not input, fflush() shall cause any unwrit-
ten data for that stream to be written to the file, and the st_ctime and st_mtime fields of the underlying file shall be marked for
update.
If stream is a null pointer, fflush() shall perform this flushing action on all streams for which the behavior is defined above.
RETURN VALUE
Upon successful completion, fflush() shall return 0; otherwise, it shall set the error indicator for the stream, return EOF, and set errno
to indicate the error.
ERRORS
The fflush() function shall fail if:
EAGAIN The O_NONBLOCK flag is set for the file descriptor underlying stream and the process would be delayed in the write operation.
EBADF The file descriptor underlying stream is not valid.
EFBIG An attempt was made to write a file that exceeds the maximum file size.
EFBIG An attempt was made to write a file that exceeds the process' file size limit.
EFBIG The file is a regular file and an attempt was made to write at or beyond the offset maximum associated with the corresponding
stream.
EINTR The fflush() function was interrupted by a signal.
EIO The process is a member of a background process group attempting to write to its controlling terminal, TOSTOP is set, the process is
neither ignoring nor blocking SIGTTOU, and the process group of the process is orphaned. This error may also be returned under
implementation-defined conditions.
ENOSPC There was no free space remaining on the device containing the file.
EPIPE An attempt is made to write to a pipe or FIFO that is not open for reading by any process. A SIGPIPE signal shall also be sent to
the thread.
The fflush() function may fail if:
ENXIO A request was made of a nonexistent device, or the request was outside the capabilities of the device.
The following sections are informative.
EXAMPLES
Sending Prompts to Standard Output
The following example uses printf() calls to print a series of prompts for information the user must enter from standard input. The
fflush() calls force the output to standard output. The fflush() function is used because standard output is usually buffered and the
prompt may not immediately be printed on the output or terminal. The gets() calls read strings from standard input and place the results in
variables, for use later in the program.
#include <stdio.h>
...
char user[100];
char oldpasswd[100];
char newpasswd[100];
...
printf("User name: ");
fflush(stdout);
gets(user);
printf("Old password: ");
fflush(stdout);
gets(oldpasswd);
printf("New password: ");
fflush(stdout);
gets(newpasswd);
...
APPLICATION USAGE
None.
RATIONALE
Data buffered by the system may make determining the validity of the position of the current file descriptor impractical. Thus, enforcing
the repositioning of the file descriptor after fflush() on streams open for read() is not mandated by IEEE Std 1003.1-2001.
FUTURE DIRECTIONS
None.
SEE ALSO
getrlimit(), ulimit(), the Base Definitions volume of IEEE Std 1003.1-2001, <stdio.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE
and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
online at http://www.opengroup.org/unix/online.html .
IEEE /The Open Group 2003 FFLUSH(3P)