Random useless Linux tips

List of random tips

They can be distro specific, unspecific, cryptic, easy to read. It doesn't matter. Instead of scribbling your tips on a personal file, dump them here.

• To find more info about the USE flags of package X: emerge gentoolkit && equery uses X
• Find info about any media file : emerge mplayer add to ~/.bashrc : idmedia(){ mplayer -identify -frames 0 -ao null -vo null -vc dummy "$@" 2>/dev/null | grep ID_ } ID_AUDIO_ID=0 ID_FILENAME=/media/mp3/Mortal love - All the beauty - 07 - I want to die.mp3 ID_AUDIO_CODEC=mp3 ID_AUDIO_FORMAT=85 ID_AUDIO_BITRATE=192000 ID_AUDIO_RATE=44100 ID_AUDIO_NCH=2 ID_LENGTH=591
  • Burn encrypted CDs with dm-crypt : cat some.iso | aespipe -H sha256 -e aes256 > some-encrypted.iso burn it with cdrecord (or losetup /dev/loop0 some-encrypted.iso) cryptsetup -c aes -s 256 -h sha256 create cdrom /dev/loop0 Password: (the password you used with aespipe) mount /dev/mapper/cdrom /mnt/cdrom and voila! of course you need device-mapper, dm-crypt target in the kernel, aes in cryptography.
    • Made a livecd or downloaded one and want to give it a testdrive before you burn it on CD(s)? USE=softemu emerge qemu qemu -cdrom /path/to/my.iso -boot d
      • Testing your all 1337 new kernel and don't want to actually boot with it so it wouldn't sleep with your girlfriend and kill your cats? USE=softemu emerge qemu qemu -kernel /bath/to/bzImage -initrd /path/to/initrd -append "kernel cmdline" -hda /dev/hda -snapshot

        Where :

        • kernel is the path to the kernel you want to try
        • initrd is the path to the initrd the kernel gonna use (optional)
        • append is the cmdline to pass to the kernel (ex : elevator=cfq video=vesafb:mtrr,ywrap,800x600@85 rootflags=nopseudo rootfstype=reiser4 rw) (optional)
        • hda/-hdb/-hdc/-hdd are either actual devices so the kernel can use or images
        • snapshot so any modifications done to the harddisk(s) wont be saved.

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        If you are using linkdotnet's 07770777 and wvdial. Add this line to wvdial.conf

        ---

        to add more virtual desktops in xfwm press ALT+INS to remove press ALT+DEL

        ---

        If for no reason you can't sync your PDA try changing permissions of the serial device chmod 666 /dev/ttyUSB1

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        How to make your linux installation autologin without gdm or kdm. (xdm doesn't allow this)

        1. First read man inittab
        2. edit /etc/inittab and change this line

        
        1:2345:respawn:/sbin/mingetty tty1
        

        to

        
        1:2345:respawn:/sbin/mingetty --autologin username tty1
        

        3. Well naturally you should now put in ~/.bash_profile the startx command. This would work but if you are logging in through a remote shell (ssh, etc.) the startx command with be issued, which is not what we want. Add the following lines in ~/.bash_profile so it issues the startx command only when logging in takes place from the console.

        
        if ["`tty`" = "/dev/console" -o "`tty`" = "/dev/vc/1"]
        then
        startx
        fi 
        

        1. init q
        2. reboot