Commands tagged description (1)

  • I put this command on my ~/.bashrc in order to learn something new about installed packages on my Debian/Ubuntu system each time I open a new terminal Show Sample Output


    2
    dpkg-query --status $(dpkg --get-selections | awk '{print NR,$1}' | grep -oP "^$( echo $[ ( ${RANDOM} % $(dpkg --get-selections| wc -l) + 1 ) ] ) \K.*")
    acavagni · 2019-06-01 13:24:07 2

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

Get AWS temporary credentials ready to export based on a MFA virtual appliance
You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token. This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use: `awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'` You must adapt the command line to include: * $MFA_IDis ARN of the virtual MFA or serial number of the physical one * TTL for the credentials

Get contents from hosts, passwd, groups even if they're in DB/LDAP/other
getent allows to get the contents of several databases in their native file format even if they are not actually in /etc. For example, if you are using a LDAP or a DB to authenticate your users, you won't find their info by catting /etc/passwd, but "getent passwd" will concatenate /etc/passwd to the LDAP/DB.

function to compute what percentage of X is Y? Where percent/100 = X/Y => percent=100*X/Y
This function make it easy to compute X/Y as a percentage. The name "wpoxiy" is an acronym of "what percentage of X is Y"

Empty Bind9 cache
Occasionally, to force zone updating, cache flush is necessary. The use of this command is better than restart the Bind9 process.

Using parcellite, indents the content of the clipboard manager
This command takes the content of a Parcellite-managed clipboard manager and add one level of indentation to it. It may be useful to indent a block of code which will enter inside another, already indented one but I use it mostly to indent code I will post in Stack Overflow questions and answers.

convert single digit to double digits
each number in a file name gets expanded to the number of digets provided as arg_1 of the arguments in rjust_file_nums. Put the funciton in the .bashrc file. Be sure to $ source ~/.bashrc so that the function will be accessible from bash.

Grabs a random image from "~/wallpapers" and sets as the background
don't bother spawning a bc process or counting the number of options, just pick a random one. 'sort -R' sorts randomly, so pick the top one.

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Display a list of RPMs installed on a particular date
Find out which RPMs were installed on a particular date. These would (naturally) include update RPMs. This example shows searching for "Thu 05 Mar" (with grep). Alternatively, pipe it to less so you can search inside less (with less's neat text highlighting of the search term): rpm -qa --queryformat '%{installtime} \"%{vendor}\" %{name}-%{version}-%{release} %{installtime:date}\n' | less # (this example) search term: Thu 05 Mar

Print stack trace of a core file without needing to enter gdb interactively
This does almost the same thing as the original, but it runs the full backtrace for _all_ the threads, which is pretty important when reporting a crash for a multithreaded software, since more often than not, the signal handler is executed in a different thread than the crash happened.


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: