Commands by dennisfaust

Commands by dennisfaust (4)

sorted by

Summarize the number of open TCP connections by state

Useful for checking the number and state of TCP connections. Show Sample Output
This is sample output - yours may be different.
```
     36 ESTABLISHED
    643 CLOSE_WAIT
      1 Foreign
      1
```
1

netstat -nt | awk '{print $6}' | sort | uniq -c | sort -n -k 1 -r

dennisfaust · 2011-06-21 16:27:19 6
Real time duplication of Apache app traffic to a second server

This takes the stream created by apache requests containing jsp and funnels them to another server. I'm using this for simulating real time traffic. The nice command gives ssh maximum CPU cycles, awk & grep strip out everything served by apache. Putting parallel on curl is important because curl is synchronous and waits for the response. Yes, I thought about using wget but it didn't seem any easier. Also, if you figure out how to run this in the background let me know. Every time I background it it stops. If you have multiple front end servers just run multiple instances of this.
This is sample output - yours may be different.
3

nice -n -20 ssh SOURCE_SERVER "tail -f /var/log/httpd/access.log " | awk '{print $7}' | grep jsp | parallel 'curl TARGET_SERVER{} 2>&1 /dev/null'

dennisfaust · 2011-05-09 19:32:40 5
cut with tab or other white space chars

cut -f1 -d\<TAB>
This is sample output - yours may be different.
-2

cut -f1 -d"<TAB>"

dennisfaust · 2011-05-05 18:17:36 7
Diff files over SSH

Sometimes you need to compare two config files on different servers. Put the file names into the above script and let 'er rip.
This is sample output - yours may be different.
3

Diff files over SSH: ssh [login]@[host] "cat [remote file]" | diff - "[local file]"

dennisfaust · 2011-04-28 16:59:56 14

What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again. 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.

Share Your Commands

Check These Out

Summarise the size of all files matching a simple regex

Use the find command to match certain files and summarise their total size in KBytes.

shows the full path of shell commands

generate a telephone keypad

seems a useless command ...

Disable WoL on eth0

See system users

journalctl -f

a tail -f variant of systemd journal. Follow the most recent updates or if events are appended to the journal

Check if a remote port is up using dnstools.com (i.e. from behind a firewall/proxy)

Shell function; returns 0 if the port is up, 1 otherwise (check $? after executing). First parameter: IP address/hostname Second parameter: port number There is no error checking for the input parameters.

Change the homepage of Firefox

This command modifies the preferences file of Firefox that is located in .mozilla/firefox/*.default/prefs.js. It edits the file with sed and the -i option. Then it searches the string "browser.startup.homepage", and the string next to it (second string). Finally, it replaces the second string with the new homepage, that is http://sliceoflinux.com in the example. It doesn't work if you haven't set any homepage.

Create a Multi-Part Archive Without Proprietary Junkware

Leave it to a proprietary software vendor to turn a cheap and easy parlor trick into a selling point. "Hey guys, why don't we turn our _collection of multiple files_ into a *collection of multiple files*!!" Extract the ^above with this: $ cat pics.tar.gz.??? | tar xzv ^extract on any Unix - no need to install junkware! (If you must make proprietary software, at least make it do something *new*) if [ -e windows ]; then use 7-Zip

Re-emerge all ebuilds with missing files (Gentoo Linux)

Stay in the loop…

Follow the Tweets.

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.

» http://twitter.com/commandlinefu
» http://twitter.com/commandlinefu3
» http://twitter.com/commandlinefu10

Subscribe to the feeds.

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:

» all commands
» commands with 3 up-votes (commandlinefu3)
» commands with 10 up-votes (commandlinefu10)
» commands by dennisfaust