Sponsored Content
Full Discussion: Non-blocking pipe
Top Forums Shell Programming and Scripting Non-blocking pipe Post 302285962 by Corona688 on Tuesday 10th of February 2009 02:43:52 AM
Old 02-10-2009
The && will cause the shell to wait before running the command after it, and should any of them fail, none of the ones after it will run. && is a conditional, it's not a background statement. Also, is there any particular reason that string of commands is all in one line? And what is 'echo exec' for, did you mean for that to be without the echo?

I don't think there's any point trying to open it as a FD in the shell if you're trying to save time, since the shell will wait for the reader to open the pipe anyway. Once it does, all three processes will get the same pipe, which I doubt is what you want. at which point all three processes will get copies of the same pipe, not queue up.

This sort of code, on the other hand, will wait for the pipe, launch a process, then immediately wait on the pipe again without waiting for the launched process to finish:
Code:
echo a > fifo &
echo b > fifo &
echo c > fifo &

 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

blocking domains

Dear All , Kindly note I have sun solaries 7 . I want to block a domain who keep sending emails to my domain and users . thanks (1 Reply)
Discussion started by: tamemi
1 Replies

2. IP Networking

School Blocking

I'm in highschool. They blocked my favorite site. How do I disable websense without getting caught on that particular webpage? Is it even possible? *twitch* I would also like to get as much UNIX for beginners information, so if someone might point me in the right direction so I don't have to read... (1 Reply)
Discussion started by: Satine
1 Replies

3. IP Networking

blocking DHCP

I've got a legit DHCP server on my network. I've got a 3550 as my VTP server providing 4 vlans to 4 2950 switches. If somebody were to plug into one of those vlans with a DHCP server configured then it would throw off my whole network. How could i block the DHCP server that could plug into the... (2 Replies)
Discussion started by: byblyk
2 Replies

4. Shell Programming and Scripting

Reading from blocking fifo pipe in shell script

Hi!! I have a problem reading from a fifo pipe in shell script. The idea is simple, I have a C program with two pipe files: An input pipe I use to send commands in shell script to the C program (echo "command" > input.pipe) An output pipe that I read the result of the command also in... (4 Replies)
Discussion started by: victorin
4 Replies

5. UNIX for Advanced & Expert Users

ps blocking

Hi Folks I have been debugging a script that is called every thirty seconds. Basically it is doing a ps, well two actually, one to file (read by the getline below) and the other into a pipe. The one into the pipe is: - V_SYSVPS=/usr/sysv/bin/ps $V_SYSVPS -p$PIDLIST -o$PSARGS... (0 Replies)
Discussion started by: steadyonabix
0 Replies

6. UNIX for Dummies Questions & Answers

Blocking signals

I know how to add signal to a set. But what if I want to add 2 or 3 signals to the set. I know I can use sigaddset (&set,SIGBUS)....but what if I want to add SIGBUS and SIGALRM at once. Do i have to do it like this.. sigaddset (&set,SIGBUS); sigaddset (&set,SIGALRM); Is there another way to... (0 Replies)
Discussion started by: joker40
0 Replies

7. Shell Programming and Scripting

Replace pipe with Broken Pipe

Hi All , Is there any way to replace the pipe ( | ) with the broken pipe (0xA6) in unix (1 Reply)
Discussion started by: saj
1 Replies

8. IP Networking

ping blocking

Hi I am starting to practice nmap for my own education. Now I created two host in virtual box. Bot are scientific linux, one in installed as web server and the other as developing station. I tried to run nmap on so I did nmap on their IP address, I got an answer that ip is down or that... (8 Replies)
Discussion started by: programAngel
8 Replies

9. Shell Programming and Scripting

How to ignore Pipe in Pipe delimited file?

Hi guys, I need to know how i can ignore Pipe '|' if Pipe is coming as a column in Pipe delimited file for eg: file 1: xx|yy|"xyz|zzz"|zzz|12... using below awk command awk 'BEGIN {FS=OFS="|" } print $3 i would get xyz But i want as : xyz|zzz to consider as whole column... (13 Replies)
Discussion started by: rohit_shinez
13 Replies

10. Programming

Which are blocking and non-blocking api's in sockets in C ?

among the below socket programming api's, please let me know which are blocking and non-blocking. socket accept bind listen write read close (2 Replies)
Discussion started by: VSSajjan
2 Replies
echo(1B)					     SunOS/BSD Compatibility Package Commands						  echo(1B)

NAME
echo - echo arguments to standard output SYNOPSIS
/usr/ucb/echo [-n] [argument] DESCRIPTION
echo writes its arguments, separated by BLANKs and terminated by a NEWLINE, to the standard output. echo is useful for producing diagnostics in command files and for sending known data into a pipe, and for displaying the contents of envi- ronment variables. For example, you can use echo to determine how many subdirectories below the root directory (/) is your current directory, as follows: o echo your current-working-directory's full pathname o pipe the output through tr to translate the path's embedded slash-characters into space-characters o pipe that output through wc -w for a count of the names in your path. example% /usr/bin/echo "echo $PWD | tr '/' ' ' | wc -w" See tr(1) and wc(1) for their functionality. The shells csh(1), ksh(1), and sh(1), each have an echo built-in command, which, by default, will have precedence, and will be invoked if the user calls echo without a full pathname. /usr/ucb/echo and csh's echo() have an -n option, but do not understand back-slashed escape characters. sh's echo(), ksh's echo(), and /usr/bin/echo, on the other hand, understand the black-slashed escape characters, and ksh's echo() also understands a as the audible bell character; however, these commands do not have an -n option. OPTIONS
-n Do not add the NEWLINE to the output. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWscpu | +-----------------------------+-----------------------------+ SEE ALSO
csh(1), echo(1), ksh(1), sh(1), tr(1), wc(1), attributes(5) NOTES
The -n option is a transition aid for BSD applications, and may not be supported in future releases. SunOS 5.10 3 Aug 1994 echo(1B)
All times are GMT -4. The time now is 07:13 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy