What return code are you trying to capture?
What are you trying to capture in the log file? (What you have seems to want to capture the output from the echo commands, but not the output from the ls command.)
It would seem that:
would be much simpler than what you're doing and produce the same results.
I want to display output and stderr to both display and the log file. [edit] sorry, original post forgot to mention display [/edit]
I need to use tee for that.
I also want to capture the return code of each command (ie echo, ls, cp, whatever). If I use:
<command> 2>&1 |tee -a <log>
then when I check $? I get the return code for tee.
So I found the logic for named pipes, and the above example seemed to work most of the time.
Then I hit this "side case?" Not really sure.
FYI: I did just find something on the web that helped.
Changed my code to this (added the exec), and now it works
(soo confused. )
From what I understand, the named pipe thinks that after the ls (or cp, or mv), that I'm all done with it. (this occurs whether I send the output of the ls, cp, or mv to the PIPE or not). By throwing the exec 5>$PIPE in there, it seems to trick it into expecting more input ???
Hi All,
I am facing a vague issue while trying to make two process talk to each
other using named pipe.
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 =... (1 Reply)
Hi All,
I am facing a vague issue while trying to make two process talk to each
other using named pipe.
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)
Gurus,
I've a File Transaction Server, which communicates with other servers and performs some processing.It uses many Named PIPE's.
By mistake i copied a named PIPE into a text file.
I heard that PIPE files shouldn't be copied.Isn't it?
Since it's a production box, i'm afraid on... (2 Replies)
I want to copy the contents of a named pipe to a file. I have tried using:
cat pipe.p >> transcript.log
but I have been unsuccessful, any ideas? (4 Replies)
Hello,
On my machine, all mail is stored in my /var/spool/mail.
IS there a way to direct all mail that goes there into a namep pipe?
Thank you,
Dado (4 Replies)
I would like to pipe (redirect ? - what is the right term?) the output of my script to a file named with the current date.
If I run this at a command prompt:
date +'%Y%m%d"
...it returns "20110429"
OK, that's good... so I try:
./script.sh > "'date +%Y%m%d'.csv"
I get a file... (1 Reply)
Hi,
I want to use a Named pipe to get input from a growing file for further processing. When I prototype this scenario using a while loop, the data is not written to the named pipe.
This the script I use to get data into the Named pipe:
#!/bin/ksh
mkfifo pipe
while (( n <= 10 ))
do
echo... (2 Replies)
Hi,
I am getting data into a Named pipe. Does Named pipe have any size restriction; I know it does not have any storage and it just passes on the data to the next process.
I want to know, if there will be a difference in the Named pipe performance if the data input is more. (I am using DB2... (1 Reply)
Hi All !
I try to collect importent events from syslog and in my
syslog conf, there is something like this:
*.* |/logs/ipes/SLpipe1
I have a program, which opens this pipe and reads the messages from it.
But how this pipe works ? Where can I probably read something about the details,... (3 Replies)
Hi ALL,
How can I test a given file name exists and if it is a named pipe file in shell script ?
Thanks............ (2 Replies)
Discussion started by: mycode.in
2 Replies
LEARN ABOUT PLAN9
pipe
PIPE(2) System Calls Manual PIPE(2)NAME
pipe - create an interprocess channel
SYNOPSIS
#include <u.h>
#include <libc.h>
int pipe(int fd[2])
DESCRIPTION
Pipe creates a buffered channel for interprocess I/O communication. Two file descriptors are returned in fd. Data written to fd[1] is
available for reading from fd[0] and data written to fd[0] is available for reading from fd[1].
After the pipe has been established, cooperating processes created by subsequent fork(2) calls may pass data through the pipe with read and
write calls. The bytes placed on a pipe by one write are contiguous even if many processes are writing. Write boundaries are preserved:
each read terminates when the read buffer is full or after reading the last byte of a write, whichever comes first.
The number of bytes available to a read(2) is reported in the Length field returned by fstat or dirfstat on a pipe (see stat(2)).
When all the data has been read from a pipe and the writer has closed the pipe or exited,read(2) will return 0 bytes. Writes to a pipe with no reader will generate a note sys: write on closed pipe.
SOURCE
/sys/src/libc/9syscall
SEE ALSO intro(2), read(2), pipe(3)DIAGNOSTICS
Sets errstr.
BUGS
If a read or a write of a pipe is interrupted, some unknown number of bytes may have been transferred.
When a read from a pipe returns 0 bytes, it usually means end of file but is indistinguishable from reading the result of an explicit write
of zero bytes.
PIPE(2)
03-19-2014
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