Sponsored Content
Full Discussion: Problems understanding pipes
Top Forums Programming Problems understanding pipes Post 302562727 by Corona688 on Friday 7th of October 2011 10:20:58 PM
Old 10-07-2011
Are you checking for builtins after you fork? Smilie You should check before. The whole point is that builtins don't need fork at all since they can happen wholly inside the shell.

I don't understand why you'd be using builtins in the middle of a pipe chain in the first place. They don't work there in csh. Unless you're trying to build in things like cat, which I don't think is a good idea.

Of course external commands must exist to use external commands. What's wrong with that? Smilie
 

10 More Discussions You Might Find Interesting

1. Filesystems, Disks and Memory

PIPEs and Named PIPEs (FIFO) Buffer size

Hello! How I can increase or decrease predefined pipe buffer size? System FreeBSD 4.9 and RedHat Linux 9.0 Thanks! (1 Reply)
Discussion started by: Jus
1 Replies

2. Shell Programming and Scripting

cd using pipes

Hi, Can the cd command be invoked using pipes??? My actual question is slightly different. I am trying to run an executable from different folders and the path of these folders are obtained dynamically from the front end. Is there a way in which i can actually run the executable... (2 Replies)
Discussion started by: Sinbad
2 Replies

3. UNIX for Advanced & Expert Users

FIFO Pipes

Hi...Can anyone please guide me on FIFO Pipes in UNIX.I have lerant things like creating fifo pipes,using them for reads and writes etc.I want to know what is the maximum amount of memory that such a pipe may have? Also can anyone guide me on where to get info on this topic from? (4 Replies)
Discussion started by: tej.buch
4 Replies

4. UNIX for Advanced & Expert Users

Consolidating Pipes

This is something I've given a lot of thought to and come up with no answer. Say you have a data stream passing from a file, through process A, into process B. Process A only modifies a few bytes of the stream, then prints the rest of the stream unmodified. Is there any way to stream the file... (4 Replies)
Discussion started by: Corona688
4 Replies

5. Shell Programming and Scripting

named pipes

How to have a conversation between 2 processes using named pipes? (5 Replies)
Discussion started by: kanchan_agr
5 Replies

6. UNIX for Dummies Questions & Answers

learning about pipes!

im trying to figure out how to do the following: using pipes to combine grep and find commands to print all lines in files that start with the letter f in the current directory that contain the word "test" for example? again using pipes to combine grep and find command, how can I print all... (1 Reply)
Discussion started by: ez45
1 Replies

7. Shell Programming and Scripting

Problems understanding example code

I am really new to UNIX and programming in general and so apologies if this thread is a bit simple. I have searched and found a piece of sample code for a training program I am currently undertaking, but seeing as I am relatively new, I dont completely understand how it works. Here is the... (1 Reply)
Discussion started by: Makaer
1 Replies

8. UNIX for Dummies Questions & Answers

Problems understanding example code

I am really new to UNIX and programming in general and so apologies if this thread is a bit simple. I have searched and found a piece of sample code for a training program I am currently undertaking, but seeing as I am relatively new, I dont completely understand how it works. Here is the... (6 Replies)
Discussion started by: Makaer
6 Replies

9. Programming

Pipes in C

Hello all, I am trying to learn more about programming Unix pipes in C. I have created a pipe that does od -bc < myfile | head Now, I am trying to create od -bc < myfile | head | wc Here is my code, and I know I might be off, thats why I am here so I can get some clarification. #include... (1 Reply)
Discussion started by: petrca
1 Replies

10. Homework & Coursework Questions

Using Pipes and Redirection

Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted! 1. The problem statement, all variables and given/known data: Create a pipe to show the number of people who are logged into the system right now. Create a pipe to show... (2 Replies)
Discussion started by: lakers34kb
2 Replies
RRDCOLLECT(8)							    RRDcollect							     RRDCOLLECT(8)

NAME
RRDcollect -- Round-Robin Database Collecting Daemon. SYNOPSIS
rrdcollect [option]... DESCRIPTION
The rrdcollect daemon is responsible for fetching statistical data from various soures (listed in rrdcollect.conf), typically files under /proc/ directory. It periodically reads them and searches for patterns from configuration file. Values are then stored inside rrdtool's .rrd files. OPTIONS
RRDcollect follows the usual GNU command line syntax, with long options starting with two dashes (`-'). General options -c file --config=file Specifies which file should be read instead of default config file. -n --no-fork Program will not fork. Very useful when testing or debugging. -v --verbose Increase verbosity. This option also implies --no-fork, since you probably don't want RRDcollect in daemon mode trashing your termi- nal. RRD update options -o file --output=file Specifies file to which rrdtool(1)-style commands should be written. If file you specify is `-' (hyphen), then commans are written to standard output (this case implies --no-fork). -p --pipe --pipe=program When this option is used, RRDcollect will open pipe to rrdtool(1) program and send it update commands. If you don't give program, the compiled-in default is assumed (either `rrdtool - >/dev/null' or full path to rrdtool(1) binary). The program option can be specified as a full path or just a command name, in the latter case the program should reside on PATH. If no RRD update option is given, RRDcollect uses internal librrd routines (the preferred mode of operation). If RRDcollect is not com- piled with librrd, then it will fall back to pipe-mode. Help and information -V --version Display RRDcollect's version, compile-time options and license. -h --help Show summary of options. --usage Show short usage information. FILES
/etc/rrdcollect.conf SEE ALSO
rrdcollect.conf(5), rrdtool(1), pcre(3) BUGS
Hopefully not many... AUTHOR
Dawid Kuroczko <qnex@knm.org.pl> Artur R. Czechowski <arturcz@hell.pl> 2 September 2002 RRDcollect 0.2.10 RRDCOLLECT(8)
All times are GMT -4. The time now is 12:56 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy