I thought the C++ cout iostream and the C++ C library stdout standard I/O stream were required to be synchronized by default. I know that an application writer could use:
to disable that synchronization and make the stdout stream independent of the cout iostream, but I didn't see anything in the code samples shown in this thread indicating that cout and stdout are not synchronized in this application.
You are, of course, correct in noting that iostreams and stdio streams are not appropriate in a multi-threaded application where I/O between threads to a single stream is not coordinated. But again, this thread was just talking about flushing a (buffered) prompt written by a process before it overlays itself with a new program by invoking execl(). If you have multiple active threads running in a process when one of those threads calls execl(), that process has undefined behavior all over the place.
Last edited by Don Cragun; 11-13-2014 at 11:01 PM..
Reason: Fix typo in spelling of "coordinated".
This is for 3 os's, AIX, Solaris, and AIX, didnt want to post three seperate times on the same subject, anyways, I want to force the user MQM to su, i.e. not be able to rlogin/telnet to the box as user MQM, only login as there ID(chris for example) and su to MQM, does anyone know how to do this,... (4 Replies)
Is there a way in solaris 9 to prevent a user to login via ssh, telnet, rlogin, and only be able to su as that user, for example
have DBA joe blow login as jblow, and then su to oracle
BUT
not vice versa
have DBA joe blow login as oralce (6 Replies)
Hi All,
Is there any way to append a newline character at the end of a file(coma-separated file), through shell script?
I need to check whether newline character exists at the end of a file, if it does not then append it.
Regards,
Krishna (1 Reply)
Hi,
I have a .txt file which has a tilde(~) in it.
All that I want is to break into a newline whenever there is an occurence of '~'.
I have tried SED to do that but I could not succeed.
I would appreciate if I can get a shell script(ksh) for this problem real quick.
Thanks in advance.
... (5 Replies)
Hi,
We have smb client running on two of the linux boxes and smb server on another linux system. During a backup operation which uses smb, read of a file was allowed while write to the same file was going on.Also simultaneous writes to the same file were allowed.Following are the settings in the... (1 Reply)
Hi,
i have a file where the end-of-file might be at the end of of a valid text line or on a new line
case a)
p q r
s t u <eof>
case b)
p q r
s t u
<eof>
case c)
p q r
s t u
<no data, only carriage return>
<eof>
I have a requirement where <eof> line should not be read if it's... (3 Replies)
Hi All,
I have file with only one record,always be only one record. as like below.
if that line contains newline end of the line..no need to add, if not just add the new line character.
END OF FILE. ROW COUNT: 7
Please help me..
Thanks, (9 Replies)
My source file is pipe delimeted file with 53 fields.In 33 rd column i am getting mutlple new line characters,dule to that record is breaking into multiple records.
Note : here record delimter also \n
sample Source file with 6 fields :
1234|abc| \nabcd \n bvd \n cde \n |678|890|900\n
... (6 Replies)
I have requirement to remove the /n ( newline ) characters from the file.
When I open file in VI .. I want to see newline char
how to display newline char .. or where can I see the content with newline char visible? (3 Replies)
Hello all,
I have maybe a simple Problem - but I do not know to handle it.
All what I want, is to write a line to file without a newline at the end. It works with "echo -n" for all lines, but not for the last one. At the end of the file is always a "0a" (hex)
My small script:
... (10 Replies)
Discussion started by: API
10 Replies
LEARN ABOUT REDHAT
stdin
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