10-31-2001
10 More Discussions You Might Find Interesting
1. UNIX for Advanced & Expert Users
Friends,
I did following exercise
$ echo '' > test
$ od -b test
$ echo "">test
$ od -b test
$echo > test
$od -b test
Every time I got the following output
0000000 012
0000001
But 012 is octal value for new line character .
Even though there is no apperent new line character... (6 Replies)
Discussion started by: j1yant
6 Replies
2. Shell Programming and Scripting
:D my first question is how can envoke filename expansion from within a shell script.. forinstance if i execute the script and it asks for a specific directory that i would like to cd to, how can i get the script to use the same file name expension as the command line..
my second question is how... (3 Replies)
Discussion started by: moxxx68
3 Replies
3. UNIX for Dummies Questions & Answers
Can anyone tell me if there is a way to remove the encryption from Data CDs by UNIX? Or does anyone know of a program that can remove the encryption?
I would much appreciate it!
Thanks,
-Peaves (2 Replies)
Discussion started by: Peaves
2 Replies
4. UNIX for Dummies Questions & Answers
Ok what is BSD exactly? I know its a type of open source but what is it exactly? (1 Reply)
Discussion started by: Corrail
1 Replies
5. Programming
Hello. I'm a complete newbie to C programming. I have a C program that wasn't written by me where I need to write some wrappers around it to automate and make it easier for a client to use. The problem is that the program accepts standard input to control the program... I'm hoping to find a simple... (6 Replies)
Discussion started by: Xeed
6 Replies
6. Shell Programming and Scripting
If given some output such as:
"I'm having a senior moment"
How do you print the last six characters to the screen?
I'm thinking with awk or sed but can't remember how. (1 Reply)
Discussion started by: stepnkev
1 Replies
7. Shell Programming and Scripting
Hey guys! This is my first post, as im new here :S
I have a simple problem for a big program.
We have a .sh to install it, but when I run the .sh in terminal like i should, It says the class is not found. I believe it has to do with the syntax, as the person who made it is not a linux pro. I... (3 Replies)
Discussion started by: Drags111
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8. UNIX for Dummies Questions & Answers
Hi Guys,
I've been learning UNIX for the past couple of days and I came across this exercise, I can't get my head around it, so I would be ever so grateful if I could receive some sort of help or direction with this.
Create a file with x amount of lines in it, the content of your choice. ... (3 Replies)
Discussion started by: aforball
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9. Shell Programming and Scripting
Hey , another question is below:
Administrator@fe038390aa60482 ~/Frank/20130509
$ c=`ls -ls`
Administrator@fe038390aa60482 ~/Frank/20130509
$ echo $c
Total 4 1 -rwxr--r-- 1 Administrator None 482 May 9 11:07 do_increment 1 -rwxr
--r-- 1 Administrator None 272 May 9 11:32 do_square 1... (2 Replies)
Discussion started by: franksunnn
2 Replies
10. Red Hat
Cheers!
In /etc/syslog.conf, if an error type is not specified, is it logged anywhere (most preferable is it logged to /var/log/messages) or not?
To be more precise I am interested in error and critical level messages. At default these errors are not specified in syslog.conf, and I need to... (6 Replies)
Discussion started by: dr1zzt3r
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LEARN ABOUT NETBSD
pcap_get_selectable_fd
PCAP_GET_SELECTABLE_FD(3) Library Functions Manual PCAP_GET_SELECTABLE_FD(3)
NAME
pcap_get_selectable_fd - get a file descriptor on which a select() can be done for a live capture
SYNOPSIS
#include <pcap/pcap.h>
int pcap_get_selectable_fd(pcap_t *p);
DESCRIPTION
pcap_get_selectable_fd() returns, on UNIX, a file descriptor number for a file descriptor on which one can do a select() or poll() to wait
for it to be possible to read packets without blocking, if such a descriptor exists, or -1, if no such descriptor exists. Some network
devices opened with pcap_create() and pcap_activate(), or with pcap_open_live(), do not support select() or poll() (for example, regular
network devices on FreeBSD 4.3 and 4.4, and Endace DAG devices), so -1 is returned for those devices.
Note that on most versions of most BSDs (including Mac OS X) select() and poll() do not work correctly on BPF devices;
pcap_get_selectable_fd() will return a file descriptor on most of those versions (the exceptions being FreeBSD 4.3 and 4.4), a simple
select() or poll() will not return even after the read timeout expires. To work around this, an application that uses select() or poll()
to wait for packets to arrive must put the pcap_t in non-blocking mode, and must arrange that the select() or poll() have a timeout less
than or equal to the read timeout, and must try to read packets after that timeout expires, regardless of whether select() or poll() indi-
cated that the file descriptor for the pcap_t is ready to be read or not. (That workaround will not work in FreeBSD 4.3 and later; how-
ever, in FreeBSD 4.6 and later, select() and poll() work correctly on BPF devices, so the workaround isn't necessary, although it does no
harm.)
Note also that poll() doesn't work on character special files, including BPF devices, in Mac OS X 10.4 and 10.5, so, while select() can be
used on the descriptor returned by pcap_get_selectable_fd(), poll() cannot be used on it those versions of Mac OS X. Kqueues also don't
work on that descriptor. poll(), but not kqueues, work on that descriptor in Mac OS X releases prior to 10.4; poll() and kqueues work on
that descriptor in Mac OS X 10.6 and later.
pcap_get_selectable_fd() is not available on Windows.
RETURN VALUE
A selectable file descriptor is returned if one exists; otherwise, -1 is returned.
SEE ALSO
pcap(3), select(2), poll(2)
5 April 2008 PCAP_GET_SELECTABLE_FD(3)