What's the deal with all the different UIDs a process can have?
Real UID, effective UID, and some systems even have a "saved UID". What's the purpose of all these, especially the last one? ...
linux
Migrating a Character Based Oracle Form
I have an OLD server running DG/UX that will in the near future be unsupported. I have some character based oracle forms that need to be migrated off of this machine. Does anyone know what sort of migration strategy Oralce has for upgrading these Character Based reports. It doesnt have to be the newest version, it doesnt even have to be ...
What's a tcpdump one-liner to dump a TCP stream that matches a given substring?
Is there a quick tcpdump one-liner to print out a TCP stream that matches a particular substring -- or, if that's not easy, how about printing out just the single TCP packet that matches the substring? ...
What Linux/Unix commands are outdated and have powerful alternatives?
Today I discovered you can make less act like tail -f. less filename, then press Shift-F to start follow mode. Just like tail, but you have all the added features of less - like scrolling, searching, and the highlighting of search hits. I've been watching log files with tail for years. This just made me ponder: are there other comm...
writing Code::Blocks plugin
where will I find documentation for developing plug-in for Code::Blocks? Also, is there a comprehensive documentation for the Code::Blocks source code which I can use to modify the source and to add desirable functionalities to the Code::Blocks IDE ...
Getting The Full Result from "ps"
Hi, How do I get the full width result for the *nix command "ps"? I know we can specify something like "--cols 1000" but is there anyway I can the columns and just print out everything? ...
Equivalent of %~dp0 in sh
I'm converting some Windows batch files to Unix scripts using sh. I have problems because some behavior is dependent on the %~dp0 macro available in batch files. Is there any sh equivalent to this? Any way to obtain the directory where the executing script lives? ...
how do you manage servers' root passwords
In our administration team, everyone knows root passwords for all client server but what we do , if one of the team is not still working with us he has still our passwords and we have to change them all, every time someone leave us , now we are using ssh keys, unstead of passwords, but this is not helpful if we have to do something o...
Can syslog Performance Be Improved?
We have an application on Linux that used the syslog mechanism. After a week spent trying to figure out why this application was running slower than expected, we discovered that if we eliminated syslog, and just wrote directly to a log file, performance improved dramatically. I understand why syslog is slower than direct file writes. ...
Process text files ftp'ed into a set of directories in a hosted server
The situation is as follows: A series of remote workstations collect field data and ftp the collected field data to a server through ftp. The data is sent as a CSV file which is stored in a unique directory for each workstation in the FTP server. Each workstation sends a new update every 10 minutes, causing the previous data to be over...
How to discard incoming packets in raw socket?
I'm writing a C/C++ application under Linux that reads data from a raw socket (for ICMP packets). Question: is there a way to discard all data that is still queued on the socket? The problem is that after sleeping for a while, there is data queued up on the socket which I'm not interested in; so it would be best to just tell the socket ...
How to start Linux Programming
I am working on C++ and COM/ATL in Windows from last few years. Now I want to shift to Linux Programming. I know basic architecture of Linux. I did some of the projects which are using ncurses, sockets and audio libraries(Terminal Applications). On which tool I should be familiar to start with projects. In windows I have started with Win...
Howto do python command-line autocompletion but NOT only at the beginning of a string
Python, through it's readline bindings allows for great command-line autocompletion (as described in here). But, the completion only seems to work at the beginning of strings. If you want to match the middle or end of a string readline doesn't work. I would like to autocomplete strings, in a command-line python program by matching wha...
From what Linux kernel/libc version is Java Runtime.exec() safe with regards to memory?
At work one of our target platforms is a resource constrained mini-server running Linux (kernel 2.6.13, custom distribution based on an old Fedora Core). The application is written in Java (Sun JDK 1.6_04). The Linux OOM killer is configured to kill processes when memory usage exceeds 160MB. Even during high load our application never go...
Apache Virtual Host - xxx.241.214.xxx:80 has no VirtualHosts
Hi, I'm trying to set up a virtual host on a new VPS using apache 2.x on a Ubuntu server. When starting apache I get the error " xxx.241.214.xxx:80 has no VirtualHosts", and the url for the site still points to the default location which means my virtual host file isn't taking effect: <VirtualHost xxx.241.214.xxx:80> ServerName xxx.co...
Remove a symlink to a directory
I have a symlink to an important directory. I want top get rid of that symlink, while keeping the directory behind it. I tried 'rm' and get back "rm: cannot remove 'foo'". I tried 'rmdir' and got back "rmdir: failed to remove 'foo': Directory not empty" I then progressed through 'rm -f', 'rm -rf' and 'sudo rm -rf' Then I went to find...
Is there a tool to automatically fetch build dependencies under Debian or Ubuntu?
I recently downloaded the source tarball for a GTK application that I'd like to improve. It uses the standard ./configure and make build sequence. The first time through, configure reported a bunch of unmet build dependencies, such as libgnomeui-2.0. As I usually do, I had to manually go through and find the Debian *-dev package names...
How can you tell whether a file is being cached in memory in linux?
Essentially my question is, does anyone know of a utility for inspecting the buffer cache in linux? ...
Does Linux provide a monotonically increasing clock to applications
Does Linux/Unix/Posix provide an API to user-space applications to access a monotonically increasing clock, with centisecond to millisecond accuracy? On Linux, /proc/uptime provides a string-based representation of a floating point number of the number of seconds the system has been up. gettimeofday(2) does not provide a monotonically ...
Linux / C++: Get the IP Address of local computer
This Question is almost the same as the previously asked Get the IP Address of local computer-Question. However I need to find the IP address(es) of a Linux Machine. So: How do I - programmatically in C++ - detect the IP addresses of the linux server my application is running on. The servers will have at least two IP addresses and I nee...