Commands by roknir (1)

  • You can use this one-liner for a quick and dirty (more customizable) alternative to the watch command. The keys to making this work: everything exists in an infinite loop; the loop starts with a clear; the loop ends with a sleep. Enter whatever you'd like to keep an eye on in the middle. Show Sample Output


    1
    while (true); do clear; uname -n; echo ""; df -h /; echo ""; tail -5 /var/log/auth.log; echo ""; vmstat 1 5; sleep 15; done
    roknir · 2010-08-23 04:37:58 0

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

generate iso

Edit a file on a remote host using vim

Get full from half remembered commands
Show all commands having the part known by you. Eg: $apropos pdf | less

Share a terminal screen with others
If you enable multiuser, then you can permit others to share your screen session. The following conditions apply: 1. screen must be suid root; 2. "multiuser on" must be configured in ~/.screenrc; 3. control the others user(s) access with "aclchg": # ----- from ~/.screenrc-users ----- aclchg someuser +rx "#?" #enable r/o access to "someuser" aclchg someuser -x "#,at,aclchg,acladd,acldel,quit" # don't allow these aclchg otheruser +rwx "#?" # enable r/w access to "otheruser" aclchg otheruser -x "#,at,aclchg,acladd,acldel,quit" # don't allow them to use these commands # ----- After doing this (once), you start your session with: $ screen Then, the other user can join your terminal session(s) with youruserid: $ screen -r youruserid/ Note: the trailing "/" is required. Multiple users can share the same screen simultaneously, each with independent access controlled precisely with "aclchg" in the ~/.screenrc file. I use the following setup: # ~/.screenrc-base # default screenrc on any host source $HOME/.screenrc-base source $HOME/.screenrc-$HOST source $HOME/.screenrc-users # ----- Then, the base configurations are in ~/.screenrc-base; the host-specific configurations are in ~/.screenrc-$HOST, and the user configurations are in ~/.screenrc-users. The host-specific .screenrc file might contain some host-specific screen commands; e.g.: # ~/.screen-myhost # ----- screen -t 'anywhere' /bin/tcsh screen -t 'anywhere1' /bin/tcsh # ---- The .screenrc-base contains: # ~/.screenrc-base ## I find typing ^a (Control-a) awkward. So I set the escape key to CTRL-j instead of a. escape ^Jj termcapinfo xterm* ti@:te@: autodetach on zombie kr verbose on multiuser on

convert single digit to double digits
Uses 'rename' to pad zeros in front of first existing number in each filename. The "--" is not required, but it will prevent errors on filenames which start with "-". You can change the "2d" to any number you want, equaling the total numeric output: aka, 4d = ????, 8d = ????????, etc. I setup a handful of handy functions to this effect (because I couldn't figure out how to insert a var for the value) in the form of 'padnum?', such as: padnum5 () { /usr/bin/rename 's/\d+/sprintf("%05d",$&)/e' -- $@ } Which would change a file "foo-1.txt" to "foo-00001.txt"

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Most used command

View acceptable client certificate CA names asked for during SSL renegotiations
The key is to use the -prexit option at the command line, and then type "quit" instead of CTRL-C to exit OpenSSL. OpenSSL will then dump its last negotiated state, printing out the contents of the renegotiated handshake. Crucial for debugging client certificate configurations on web servers such as IIS, which renegotiate the SSL/TLS connection with the HTTP request in-flight to ask the client for a cert.

Router discovery


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: