Commands by totti (87)

  • Matched string reference in replacement text

    Use matched data and some other as replacement data Show Sample Output


    0
    echo "abcde" | sed 's/./& /g'
    totti · 2011-08-26 16:54:26 7
  • Notify on Battery power

    Works on Laptops, Desktop having communication b/w UPS & CPU Show Sample Output


    0
    NotifyOnBATTERY () { while :; do on_ac_power||notify-send "Running on BATTERY"; sleep 1m; done }
    totti · 2011-08-26 11:54:16 7
  • Download a set of files that are numbered


    0
    for i in `seq -w 1 50`; do wget --continue \ http://commandline.org.uk/images/posts/animal/$i.jpg; done
    totti · 2011-08-19 20:06:16 5
  • Get full from half remembered commands

    Show all commands having the part known by you. Eg: apropos pdf | less Show Sample Output


    2
    apropos <part_rember> | less
    totti · 2011-08-19 19:34:57 6
  • Alternative for basename using grep to extract file name

    fileName /path/to/file.ext quivalent to basename /path/to/file.ext Show Sample Output


    -1
    fileName() { echo "$1" | grep -o "[^/]*$"; }
    totti · 2011-08-19 18:16:22 3
  • Boot block devices as virtual devices in Virtual Box

    eg: VBoxManage internalcommands createrawvmdk -filename ~/.VBox_sdc.vmdk -rawdisk /dev/sdc In order to start virtual box using block devices, ( Or to boot from it) run as ROOT sudo VirtualBox Then add & select the vmdk file as a device. At last Start the virtual box. - This cmd needs to run once for a device. - See command 8936 to run with out using ROOT power and easy handling of Virtual m/c


    0
    VBoxManage internalcommands createrawvmdk -filename [path/to/file/name.vmdk] -rawdisk /dev/[block_device]
    totti · 2011-08-19 14:26:22 8
  • Find all videos under current directory using MIME a.k.a not using extension

    Videos are found using their MIME type. Thus no need to for an extension for the video file. This is a efficent version of "jnash" cmd (4086). Thanks for jnash. This cmd will only show video files while his cmd show files having "video" anywhere in path. Show Sample Output


    1
    allVideos() { find ./ -type f -print0 | xargs -0 file -iNf - | grep ": video/" | cut -d: -f1; }
    totti · 2011-08-19 11:58:59 3
  • What is the use of this switch ?

    Find the usage of a switch with out searching through the entire man page. Usage: manswitch [cmd] [switch] Eg: manswitch grep silent ____________________________ In simple words man <cmd> | grep "\-<switch>" Eg: man grep | grep "\-o" This is not a standard method but works. Show Sample Output


    1
    manswitch() { man $1 | grep -A5 "^ *\-$2"; }
    totti · 2011-08-19 08:36:54 5
  • Sort output by column

    (separator = $IFS)


    2
    ps aux | sort -nk 6
    totti · 2011-08-16 11:04:45 3
  • Check if your webserver supports gzip compression with curl


    6
    curl -I -H "Accept-Encoding: gzip,deflate" http://example.org
    totti · 2011-08-16 10:32:01 4
  • Highlight network TX, RX information change


    5
    watch -n 2 -d '/sbin/ifconfig eth0'
    totti · 2011-08-16 10:29:34 4
  • Boot from a block device without giving root privilege to Virtual Box

    Usage: VBoxBlockBoot [Virtual_Machine] [Block_device] Eg: VBoxBlockBoot WinXP /dev/sdc In another words vm=usb; usb=sdc;sudo umount /dev/$usb* ; sudo chmod 777 /dev/$usb ; VBoxManage storageattach $vm --medium ~/raw-HD-4-VB/$usb.vmdk --type hdd --storagectl "IDE Controller" --device 0 --port 0 ; VBoxManage startvm $vm Where vm --> Name of the virtual machine to start usb --> Block device to use. (/dev/sdc) This can used after setup up a boot loader on to my USB pen drive or HDD (After creating Live USB). Here root privilege is needed but not granted to Virtual Box. Thus we can access all our VM.( If we run VBox as root we can't access our VMs). Root privilege is used to - Unmount the storage device - Chmod to full access (777) Requirements:- 1. Device information file (rawvmdk file) created by the following command. Need to run only once. Not bad to run many. VBoxCreateRawDisk() { VBoxManage internalcommands createrawvmdk -filename ~/.rawHD4VB_`basename "$1"`.vmdk -rawdisk "$1"; } 2. Root privilege to umount & chmod 3. Real storage medium (ie /dev/*) (Non-virtual such as USB HD, pen drive, a partition) 4. A virtual m/c already available (here "usb") vm=usb; usb=sdc;sudo umount /dev/$usb* ; sudo chmod 777 /dev/$usb ; VBoxManage storageattach $vm --medium ~/raw-HD-4-VB/$usb.vmdk --type hdd --storagectl "IDE Controller" --device 0 --port 0 ; VBoxManage startvm $vm VBoxBlockBoot() { sudo umount "$2"*; sudo chmod 777 "$2"; VBoxManage storageattach "$1" --medium ~/.rawHD4VB_`basename "$2"`.vmdk --type hdd --storagectl "IDE Controller" --device 0 --port 0 ; VBoxManage startvm "$1"; } Show Sample Output


    0
    VBoxBlockBoot() { sudo umount "$2"*; sudo chmod 777 "$2"; VBoxManage storageattach "$1" --medium ~/.rawHD4VB_`basename "$2"`.vmdk --type hdd --storagectl "IDE Controller" --device 0 --port 0 ; VBoxManage startvm "$1";}
    totti · 2011-07-29 13:04:19 4
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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"

how many pages will my text files print on?
This gives a very rough estimate of how many pages your text files will print on. Assumes 60 lines per page, and does not take long lines into account.

Find and display most recent files using find and perl
This pipeline will find, sort and display all files based on mtime. This could be done with find | xargs, but the find | xargs pipeline will not produce correct results if the results of find are greater than xargs command line buffer. If the xargs buffer fills, xargs processes the find results in more than one batch which is not compatible with sorting. Note the "-print0" on find and "-0" switch for perl. This is the equivalent of using xargs. Don't you love perl? Note that this pipeline can be easily modified to any data produced by perl's stat operator. eg, you could sort on size, hard links, creation time, etc. Look at stat and just change the '9' to what you want. Changing the '9' to a '7' for example will sort by file size. A '3' sorts by number of links.... Use head and tail at the end of the pipeline to get oldest files or most recent. Use awk or perl -wnla for further processing. Since there is a tab between the two fields, it is very easy to process.

list files recursively by size

Find Duplicate Files (based on size first, then MD5 hash)
for OS X

Scans for open ports using telnet

Efficient count files in directory (no recursion)
$ time perl -e 'if(opendir D,"."){@a=readdir D;print $#a - 1,"\n"}' 205413 real 0m0.497s user 0m0.220s sys 0m0.268s $ time { ls |wc -l; } 205413 real 0m3.776s user 0m3.340s sys 0m0.424s ********* ** EDIT: turns out this perl liner is mostly masturbation. this is slightly faster: $ find . -maxdepth 1 | wc -l sh-3.2$ time { find . -maxdepth 1|wc -l; } 205414 real 0m0.456s user 0m0.116s sys 0m0.328s ** EDIT: now a slightly faster perl version $ perl -e 'if(opendir D,"."){++$c foreach readdir D}print $c-1,"\n"' sh-3.2$ time perl -e 'if(opendir D,"."){++$c foreach readdir D}print $c-1,"\n"' 205414 real 0m0.415s user 0m0.176s sys 0m0.232s

Remove executable bit from all files in the current directory recursively, excluding other directories
With GNU chmod at least it is that simple.

Check the current price of Bitcoin in USD

Find the most recently changed files (recursively)

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