Commands using swapon (3)

  • create an emergency swapfile when the existing swap space is getting tight

    Create a temporary file that acts as swap space. In this example it's a 1GB file at the root of the file system. This additional capacity is added to the existing swap space. Show Sample Output


    18
    sudo dd if=/dev/zero of=/swapfile bs=1024 count=1024000;sudo mkswap /swapfile; sudo swapon /swapfile
    dcabanis · 2009-05-27 21:10:50 12
  • Clean swap area after using a memory hogging application

    When you run a memory intensive application (VirtualBox, large java application, etc) swap area is used as soon as memory becomes insufficient. After you close the program, the data in swap is not put back on memory and that decreases the responsiveness. Swapoff disables the swap area and forces system to put swap data be placed in memory. Since running without a swap area might be detrimental, swapon should be used to activate swap again. Both swapoff and swapon require root privileges.


    10
    swapoff -a ; swapon -a
    alperyilmaz · 2009-03-25 03:30:41 16
  • Add temporary swap space

    In addition to a swap partition, Linux can also use a swap file. Some programs, like g++, can use huge amounts of virtual memory, requiring the temporary creation of extra space.


    8
    dd if=/dev/zero of=/swapfile bs=1M count=64; chmod 600 /swapfile; mkswap /swapfile; swapon /swapfile
    starchox · 2009-02-16 18:36:38 1170

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

Send a backup job to a remote tape drive on another machine over SSH
I use this all the time for taking manual backups of stuff i want to keep but not important enough to backup regularly.

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" }

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"

Trace and view network traffic
Trace and view network traffic. I made this far too complicated.. now fixed, thanks zolden.

Rename files in batch

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"

Create a favicon
Create a favicon suitable for use on your web site. Note: ppmtowinicon is part of libpbm, not ImageMagick.

edit hex mode in vim
return to normal mode from hex mode :%!xxd -r

Delete line number 10 from file
Very useful when the ssh key of a host has changed and ssh refuses to connect to the machine, while giving you the line number that has changed in ~/.ssh/known_hosts.

Get all links of a website

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: