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.
You can sign-in using OpenID credentials, or register a traditional username and password.
First-time OpenID users will be automatically assigned a username which can be changed after signing in.
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
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:
Just one character longer than the sed version ('FNR==5' versus -n 5p). On my system, without using "exit" or "q", the awk version is over four times faster on a ~900K file using the following timing comparison:
testfile="testfile"; for cmd in "awk 'FNR==20'" "sed -n '20p'"; do echo; echo $cmd; eval "$cmd $testfile"; for i in {1..3}; do time for j in {1..100}; do eval "$cmd $testfile" >/dev/null; done; done; done
Adding "exit" or "q" made the difference between awk and sed negligible and produced a four-fold improvement over the awk timing without the "exit".
For long files, an exit can speed things up:
awk 'FNR==5{print;exit}' <file>
Sample command to obtain a list of geographic localization for established connections, extracted from netstat. Need geoiplookup command ( part of geoip package under CentOS)
Consider this file :
laminate
this
file
with awk
hello to
commandlinefu
I can use awk substring to laminate words :
lamin
this
file
with
hello
comma
Similar to http://www.commandlinefu.com/commands/view/2000/laminate-files-line-by-line
Work for me on CentOS, grep and print ip addresses of ssh bruteforce attempts
If you run this command on a VMWare Virtual Machine, it will return the string "VMware Virtual Platform". If you run it on a physical machine, it will return nothing. Useful for having a script determine if it's running on a VM or not. Of course, you must have dmidecode installed for this to work.
Try it this way in a script: ISVM=$(dmidecode | awk '/VMware Virtual Platform/ {print $3,$4,$5}')
Then test if $ISVM has text in it, or is blank.
You're behind on your TV catch-up, but how far behind? This command tries to open mplayer against all files in the current dir. If it's a video file it will contain ID_LENGTH, which is summed and output in hours, minutes and seconds.
Someone better at awk could probably reduce this down a lot.
inputfile.txt is a space-separated textfile, 1st column contains the items (id) I want to put into my SQL statement.
39 = charactercode for single tick '
1 = first column
If inputfile.txt is a CSV-file separated by "," use FS= to define your own field-separator:
awk 'BEGIN {FS=","; }{printf "select * from table where id = %c%s%c;\n",39,$1,39; }' inputfile.txt
worked on ubuntu 9.04 and cygwin with MS netstat
After executing this, click on a window you want to track X Window events in.
Explaination: "xev will track events in the window with the following -id, which we get by greping window information obtained by xwininfo"
Show apps that use internet connection at the moment.
Can be used to discover what programms create internet traffic. Skip the part after awk to get more details, though it will not work showing only unique processes.
This version will work with other languages such as Spanish and Portuguese, if the word for "ESTABLISHED" still contain the fragment "STAB"(e.g. "ESTABELECIDO")
This corrects duplicate output from the previous command.
Can be used to discover what programms create internet traffic. Skip the part after awk to get more details.
Has anyone an idea why the uniq doesn't work propperly here (see sample output)?
I sometimes (due to mismanagement!) end up with files in a git repo which have had their modes changed, but not their content. This one-liner lets me revert the mode changes, while leaving changed-content files be, so I can commit just the actual changes made.