commandlinefu.com is the place to record those command-line gems that you return to again and again.
Delete that bloated snippets file you've been using and share your personal repository with the world. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.
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Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.
Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):
Subscribe to the feed for:
This will tell you who has the most Apache connections by IP (replace IPHERE with the actual IP you wish to check). Or if you wish, remove | grep -c IPHERE for the full list.
List top 20 IP from which TCP connection is in SYN_RECV state.
Useful on web servers to detect a syn flood attack.
Replace SYN_ with ESTA to find established connections
This command is useful when you want to know what process is responsible for a certain GUI application and what command you need to issue to launch it in terminal.
After you install/remove lots of packages, there are many packages marked with 'rc'. This script help you to purge these packages, it will save some spaces from your disk.
usefull in case of abuser/DoS attacks.
Do ls with permissions written in octal form.
Check if Fail2Ban is running on the system and alert it with a message in the terminal
The description of how the one-liner works is here at my blog:
You cannot kill zombies, as they are already dead. But if you have too many zombies then kill parent process or restart service.
You can kill zombie process using PID obtained from the above command. For example kill zombie proces having PID 4104:
# kill -9 4104
Please note that kill -9 does not guarantee to kill a zombie process.
8~osstat, $2~pid, $11~cmd