Is there already a program that reads multiple pipes or file descriptors and writes to the standard output (not splitting lines).Like cat, but reading all files simultaneously and preserving lines.It is needed to avoid coding of select/epoll loops or using multithreading in simple programs. Like "select loop for bash".
View 1 RepliesFile descriptors with pipes-Can someone help me with this three situations, what would happen?
a) a process open the same file twice and read through two file descriptors
b) a process does fork and both parent- and child-processes read parallell
c) two processes opens and read from same file.
I have a weird problem with one of my servers. When system is booted and right before I should se "INIT 2.86 starting..." message, all the messages disappear. Only kernel messages get logged to console and later login prompt, but nothing in betweek (there are 20+ services starting successfully, just without emitting a single character).I checked /proc/PID/fd of the boot script (in my case called /etc/rc.d/rc.boot but that does not matter).
The only significant difference in hardware to other servers is that this one runs RV350 AP [Radeon 9600] graphic card.Now, my question is: where could those FDs go or why are they not opened?Does anyone have a clue about this, or a hint?
We are graphing various system parameters using Cacti. One of our graphs shows hard drive reads and writes. A question came up: why do we need this graph?
View 3 Replies View RelatedI have a fileserver running 10.04 server 64bit and samba. I connect it to my desktop which is 10.04 desktop 64bit.I have the server mounted on my desktop in fstab as://10.0.0.2/share /media/share cifs guest, uid= 1000.Up until 30 June 2010 it was all fine. Now when I write the server it is very slow e.g. 2Mbps though when I read I get >100Mbps so I think my network is still ok. If i use nautilus smb://10.0.0.2/share I can write at >100Mbps and also read at >100Mbps...So any ideas why the write speed via the fstab mount samba has started to go really slowly in the last couple of days?
View 6 Replies View RelatedIs there a way to determine the IO size that is being used for reads and writes to an attached storage device? I am trying to pattern the IO sequences to storage. I have seen mentions to max_sectors_kb but the notes indicated that changing this value did not change the IO size to the storage.
View 1 Replies View RelatedI have a 6 disk mdadm RAID 10 array of Western Digital RE3 drives. IOZone and all the other tools I have tried are showing pretty lackluster reads for a six drive RAID 10 array, in the area of 200MB/s. Writes are closer to what I'd expect in that area, around 340MB/s. These drives fly with an Adaptec RAID controller, but as soon as I stick them in an mdadm array, the reads just aren't what I'd expect.
I am using what I believe to be optimal settings:
-C /dev/md2 --chunk=1024 -n 6 -l 10 -p f2 /dev/sda5 /dev/sdb5 /dev/sdc5 /dev/sdd5 /dev/sde5 /dev/sdf5
-b 4096 -E stride=256,stripe-width=768
have recently installed CentOS 5.6 Final on TWO DIFFERENT desktop PC's, and, on EITHER ONE, I can not get any sound output when using KMid to play a "standard .mid file (the file I am using to experiment with is "Canyon.mid", from the Windoze Media directory, a fairly standard midi audio file, I should think?!). I have normal audio output on both of these machines (.mp3 files, system sounds, etc.), so the specific sound cards are NOT the issue, here!I am thinking I must be missing something, as both of these PC's are completely different CPU types, etc. as well. The only significant similiarity in the two machines is the complete lack of MIDI audio output!And, yea, the soundcards are BOTH MPU-401 compatible, and they both have irq's assigned to this port (or, maybe just one has an irq assigned, I will have to double check...).
View 2 Replies View RelatedI am working on telnet session and excuting commands. I am able to redirect or store expect output to log file but now i want to store in excel file like ispreadsheet showing details of commands and its responses
View 2 Replies View RelatedI'm trying to redirect nc command output but I can't do it.
I have tried this:
And this:
But it seems doesn't work.
I need to find one RUNNING word in latest created logs.
and as soon as i will get RUNNING WORD , i have to execute another Unix Command.
I wrote following script code...
see these simple commands:
Code:
# dbus-monitor --system >> /data/eject.txt
This one works as expected ... dbus-monitor never terminates and whenever it outputs new lines, they are
[code]....
I'm using Ubuntu and I'm programing with eclipse CDT. My goal is to execute a php file and read the output to my c++ program. To do so I thought I should use fork(), dup2() and execl. When in shell, the call "php myscript.php" worked just fine, but when in c++ I tried:
execl("usr/bin/php", "php", "home/geiger/workspace/SemiServer/server_content/myscript.php", NULL);
And it didn't work (the process wasn't terminated and I got no output). I tried different version of this call, like losing the "php" string and/or drop "home/geiger" from the path string, to no better result.
I'm working on some scheduled task script files to keep nightly backups of some of our database information in place, and it's a bit annoying when they blow up. I know how to redirect stdout and stderr to a flat file I can view when I come in, and I know that 2>&1 maps them both to the same file (whatever was named in 1). However, I'm running into some cron-time situations where it's easier to have the two streams together, and other cron-time situations where it's easier to have them separated. I can't really tell which is going to happen; is there some way I could create both kinds of output file for my scripts, so that I've got a std_err only file and an interleaved std_out/std_err file?
Note: I've looked at the 'tee' command, but I don't think it will work for what I'm after. 'tee' appears to only work with stdout; I'm trying to work with stderr.
I was analyzing the Disk read using hdparm utility. This is what i got as a result.
Code:
# hdparm -t /dev/sda
/dev/sda:
Timing buffered disk reads: 108 MB in 3.04 seconds = 35.51 MB/sec
Code:
# hdparm -T /dev/sda
/dev/sda:
Timing cached reads: 3496 MB in 1.99 seconds = 1756.56 MB/sec I m not sure what does Cache read and buffered disk read mean.
On linux, is there a way to count the number of file descriptors open to a some file?
View 1 Replies View RelatedI am quite confused about the following description on fork. Could you please explain it ?The child process shall have its own copy of the parent's file descriptors. Each of the child's file descriptors shall refer to the same open file description with the corresponding file descriptor of the parent.For example, I am opening a socket and then fork. Now, does the child have a separate socket or is shares it with the parent. Does I have any impact on using it in child?
View 2 Replies View RelatedI'm working on a SBC9261 board with touchscreen, running Linux 2.6.24./dev/ttyS0 is the standard output and /dev/tty0 is the console on the touchscreen.What I would like to do is to clone the standard output to the touchscreen, so the console would be displayed twice.
It would be like :
Code:
~ $ ./whatEverScript > /dev/tty0
but the output would also appear on /dev/ttyS0.
I have nine barcode scanners, each of whose input I want to send to a separate instantiation of a program I wrote. Each device shows up as /dev/hidraw_ (I'm using Ubuntu 10.4). The problem is that they all act as simple keyboard input, and I can't seem to redirect the output from one to a specific instance of my program. I've tried something like cat /dev/hidraw5 > ./myapp, and that doesn't work. I've tried actually opening the device in my program using open("/dev/hidraw5"), and it returns success, but subsequent reads don't do anything, and the scanner output is just printed to the console.
View 1 Replies View RelatedWe make everyday a DB Mysql backup on Linux redhat Enterprise. We are using a bash shell script (and putting it in the crontab) to execute it automatically everyday. We added a line to this script telling, once the backup has completed, to find old backup files (stored on hard disk after each backup) older than x days to remove them. We use the find command (search for file type) with the mtime option and in combination with rm command. Everything runs ok but we also want to add some new code to the same line: If find command cannot find anything or fails, for example if it cannot delete file or fails, send the error message (standard error output) to an error file (like error000001 and increasing) and mail the errorxxxx file to an email address for example to admin@companyname.com. What would be the code for this issue to add it to our find command in the same bash shell script??
View 2 Replies View RelatedI am using Red Hat Enterprise Version 5. There is a ruby program which use standard input as its input (e.g. the Ruby program process input from standard input). I think standard input should be keyboard, correct?
So, I think other kinds of input (non-standard input) should not work (i.e. the ruby program should not be able to read input from such non-standard input), but actually I have tried using pipe works, I am so confused because I think pipe should be some other kinds of input -- other than standard input, why it could work? i.e. put text "123" in abc.txt with pipe, could achieve the same result as using keyboard as input to type "123" for the ruby program.
cat abc.txt | ~/test/rubysrc/foo.rb
what I am trying to do but I am not sure exactly how to do it. I want to write a shell script that will replace certain values in a file with environment specific information that it pulls from a parameters file. The paramaters file looks like the following...
[dev]
ip=10.15.109.41
name=dev1.mydomain.com
[code]...
I am learning Linux daemon programming and write a simple daemon program. The issue is no data is written to the log file (/var/tmp/simpledeamon.log) though the file is successfully created (it's file size is zero from ls -l output). Could someone kindly point out the error in my program,The code is based on the Devin Watson's article at Here is the code:
// simplydaemon.cpp
// A simple Linux daemon.
#include <sys/types.h>
[code]...
you have to read from many devices separate devices and make it look like a single one. It sounds very much like a device driver to me, perhaps... but getting my hands dirty with kernel code sounds like a daunting task for me that I've never done it...
View 2 Replies View RelatedI have a requirement like this:Cut the characters from each line of a file with following positions: 21-24, 25-34 ,111-120.Thse fields now need to be placed in a tab delimited output file.Currently this is how I am achieving it:
#!/bin/sh
cat newsmaple.txt | cut -c 21-24 > out1.txt
cat newsmaple.txt | cut -c 25-34 >out2.txt
[code]....
I have run into a limit of 1024 file descriptors. I have searched a lot and have tried various solutions.How can the max file descriptors be set in Ubuntu?
View 1 Replies View RelatedCan someone please tell me how to permanently increase the default file descriptors limit on RHEL4?right now ulimit -n is 1024...I'd like to increase it to around 10000
View 1 Replies View RelatedIts my Friend Problem .any one can tells that how can the file descriptors limits can be raise for the squid. In cache.log running out of file descriptors warning is coming.
View 3 Replies View RelatedI am using sabayon 5 - 32bit OS. I experience dullness and sluggish performance now and then.So number of free file descriptors is constantly zero , checked by utilising a while loop sleeping for 5 secs.would this be the root cause of the sluggishness I face in accessing application (media player)Also USB transfer is very very slow and sometimes it gets stuck
View 1 Replies View RelatedI am looking for a program that will take multiple avi files and join them into one file
View 8 Replies View Related