which hangs on the final echo command when I run it.
Interestingly, if I comment out the ls, or either echo command, it works fine.
So I'm trying to understand what's happening here. Hoping somebody could explain?
What I'm trying to do:
- capture stdout and stderr into a log file. [edit] correction: want to capture stdout and sterr to both display and log file[/edit]
- need to capture the return code of the command as well (ie $?) (hence why I'm mucking around with PIPE's so I can displace the tee command).
It seems to work sometimes, and then hang on other occasions, and I haven't found a pattern to it yet.
Hoping anyone can shed light on this - or provide a suitable work around.
Thanks!
[edit]
more specific version info:
Sun4u sparc SUNW
SPARC-Enterprise SunOS
5.10
uname -v
returns:
Generic_147440-02
[/edit]
[edit]
Seems as soon as I do an ls, cp, mv or other disk access, it hangs on the next command?
[/edit]
Last edited by Ditto; 03-19-2014 at 05:19 PM..
Reason: version
Hi All,
I am facing a vague issue while trying to make two process talk to each
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read process
=========
The process which reads, basically creates FIFO using
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It then opens the pipe using open func - fd =... (1 Reply)
Hi All,
I am facing a vague issue while trying to make two process talk to each
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read process
=========
The process which reads, basically creates FIFO using
mkfifo - ret_val = mkfifo(HALF_DUPLEX, 0666) func.
It then opens the pipe using open func - fd = open... (2 Replies)
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Discussion started by: mycode.in
2 Replies
LEARN ABOUT BSD
pipe
PIPE(2) System Calls Manual PIPE(2)NAME
pipe - create an interprocess communication channel
SYNOPSIS
pipe(fildes)
int fildes[2];
DESCRIPTION
The pipe system call creates an I/O mechanism called a pipe. The file descriptors returned can be used in read and write operations. When
the pipe is written using the descriptor fildes[1] up to 4096 bytes of data are buffered before the writing process is suspended. A read
using the descriptor fildes[0] will pick up the data.
It is assumed that after the pipe has been set up, two (or more) cooperating processes (created by subsequent fork calls) will pass data
through the pipe with read and write calls.
The shell has a syntax to set up a linear array of processes connected by pipes.
Read calls on an empty pipe (no buffered data) with only one end (all write file descriptors closed) returns an end-of-file.
Pipes are really a special case of the socketpair(2) call and, in fact, are implemented as such in the system.
A signal is generated if a write on a pipe with only one end is attempted.
RETURN VALUE
The function value zero is returned if the pipe was created; -1 if an error occurred.
ERRORS
The pipe call will fail if:
[EMFILE] Too many descriptors are active.
[ENFILE] The system file table is full.
[EFAULT] The fildes buffer is in an invalid area of the process's address space.
SEE ALSO sh(1), read(2), write(2), fork(2), socketpair(2)BUGS
Should more than 4096 bytes be necessary in any pipe among a loop of processes, deadlock will occur.
4th Berkeley Distribution August 26, 1985 PIPE(2)
03-19-2014
Named pipe hanging?
