Commands by alf (5)

  • This may be listed already but this command is useful to untar a specific directory to a different server.


    0
    cat tarfile.tar.gz | ssh server.com " cd /tmp; tar xvzf - directory/i/want"
    alf · 2011-02-11 17:10:01 1
  • Some servers don't have ssh-copy-id, this works in those cases. It will ask for the destination server, this can be IP, hostname, or user@hostname if different from current user. Ssh keygen will let you know if a pubkey already exists on your system and you can opt to not overwrite it.


    -2
    echo 'Host or User@Host?:'; read newserver && ssh-keygen -N "" -t rsa -f ~/.ssh/id_rsa ; ssh $newserver cat <~/.ssh/id_rsa.pub ">>" ~/.ssh/authorized_keys ; ssh $newserver
    alf · 2010-05-07 06:24:53 1
  • Interfaces like lo can be omitted from the beginning, there are probably better ways of doing this, i'm a noob at awk. Show Sample Output


    5
    ifconfig -a| awk '/^wlan|^eth|^lo/ {;a=$1;FS=":"; nextline=NR+1; next}{ if (NR==nextline) { split($2,b," ")}{ if ($2 ~ /[0-9]\./) {print a,b[1]}; FS=" "}}'
    alf · 2010-04-15 04:34:28 3
  • Will edit *.db files in the same directory with todays date. Useful for doing a mass update to domains on a nameserver, adding spf records, etc. Looks for a string starting with 200 or 201 followed by 7 numbers, and replaces with todays date. This won't overwrite Ip's but i would still do some double checking after running this. Make sure your server's date is correct, otherwise insert your own serial number. rndc reload should usually follow this command.


    7
    sed -i 's/20[0-1][0-9]\{7\}/'`date +%Y%m%d%I`'/g' *.db
    alf · 2010-03-24 07:28:58 2
  • Bash scrip to test if a server is up, you can use this before wget'ing a file to make sure a blank one isn't downloaded.


    -1
    if [ "$(ping -q -c1 google.com)" ];then wget -mnd -q http://www.google.com/intl/en_ALL/images/logo.gif ;fi
    alf · 2010-03-23 04:15:03 7

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Converts all pngs in a folder to webp using all available cores
As an alternative to the above command, this one ditches the unnecessary and complicated for loop in favor of a way faster multi-core approach for a task that's more CPU than I/O intensive, making it a perfect suite for GNU parallel

Find and delete oldest file of specific types in directory tree
This works on my ubuntu/debian machines. I suspect other distros need some tweaking of sort and cut. I am sure someone could provide a shorter/faster version.

ettercap..
There weren't any one liners for ettercap on this site... tisk tisk :-) (of course you'll have to plugin your own values for the variables..)

Rolling upgrades via aptitude
This has been my "sysupgrade" alias since ca. 2006, first used on Debian Sid, then Sabayon, and it still does its duty on Mint nowadays without breaking stuff.

Remove all .svn folders
With the plus instead of semicolon, find builds the (eg.) rm command like xargs does - invokes as few extra processes as possible.

get xclip to own the clipboard contents
"Copying" things to the X clipboard doesn't normally create a copy. Rather the data to be 'copied' is referenced. This means that if the application that you 'copied' stuff from is closed, that data is lost. If the application that you 'copied' from is suspended with CTRL-Z, there could be some issues if you try to paste it into something. This command will create a copy of referenced data and have xclip be the provider of it, so you can then go ahead and close the app that contains the original information. Caveat: I'm not sure if this is binary-safe (though i would expect it to be), and don't know what would happen if you used it to clip a 20 meg gimp image. This technique becomes more convenient if you set it up as an action in a clipboard manager (eg klipper, parcellite). Some of these applets can take automatic action based on a variety of parameters, so you could probably just get it to always own the clipped data whenever data is clipped.

check open ports without netstat or lsof

Schedule Nice Background Commands That Won't Die on Logout - Alternative to nohup and at
Check out the usage of 'trap', you may not have seen this one much. This command provides a way to schedule commands at certain times by running them after sleep finishes sleeping. In the example 'sleep 2h' sleeps for 2 hours. What is cool about this command is that it uses the 'trap' builtin bash command to remove the SIGHUP trap that normally exits all processes started by the shell upon logout. The 'trap 1' command then restores the normal SIGHUP behaviour. It also uses the 'nice -n 19' command which causes the sleep process to be run with minimal CPU. Further, it runs all the commands within the 2nd parentheses in the background. This is sweet cuz you can fire off as many of these as you want. Very helpful for shell scripts.

Find the files that contain a certain term
Simple use of find and grep to recursively search a directory for files that contain a certain term.

vim insert current filename
insert filename Normal mode: "%p Insert mode: %


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