McGurk's Linux tips

Alternatives

System Debian


ls /etc/alternatives
update-alternatives --display x-www-browser
sudo update-alternatives --config x-www-browser

Show data as hexdecimal format

shell *


od -tx1 file.txt
xxd file.txt
hexdump file.txt

Install package without depencies

dpkg *


dpkg --force-all -i [package]

/var/lib/dpkg/status


-Search broken package
-Remove lines:
  Depends:
  Pre-Depends:
  Recommends:
  Suggests:
  Conflicts:

Make your own patch

Patch *


diff -rupN a/ b/ > own.patch

How do I su to another user and run an X application?

Xorg *


xhost +LOCAL:

Replace string in files

Shell *


sed -i 's/string1/string2/g' file.txt


sed -i 's/old-word/new-word/g' *.txt


grep -rl matchstring somedir/ | xargs sed -i 's/string1/string2/g'

WLAN by hand

Network * /etc/wpa_supplicant.conf


# Simple case: WPA-PSK, PSK as an ASCII passphrase, allow all valid ciphers
network={
	ssid="simple"
	psk="very secret passphrase"
	priority=5
}
# The higher the priority the sooner we are matched

/etc/network/interfaces


#auto wlan0
iface wlan0 inet dhcp
up wpa_supplicant -iwlan0 -c/etc/wpa_supplicant.conf
down killall wpa_supplicant


# Change Network Interface device name
ip link set dev eth1 name wlan0

How to remove very broken packages


cd /var/lib/dpkg/info
sudo rm flashplugin-nonfree.*


sudo dpkg --remove --force-remove-reinstreq flashplugin-nonfree

Hexdump

Shell *


xxd [file]
echo "test" | xxd

Serial console

Console * /etc/inittab


# Example how to put a getty on a serial line (for a terminal)
#
T0:23:respawn:/sbin/getty -L ttyS0 9600 vt100
#T1:23:respawn:/sbin/getty -L ttyS1 9600 vt100


sudo init q

/etc/issue (optional)


Debian GNU/Linux 6.0 \n \l at \b bps (\U)

/boot/grub/grub.conf


# Everything to serial console:
        kernel /vmlinuz-2.4.20-24.9 ro root=LABEL=/ console=ttyS0,38400

Info:


 dmesg|grep tty
  [    1.917029] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
  [    1.955642] 00:07: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
 
 setserial -a -q /dev/ttyS0
  /dev/ttyS0, Line 0, UART: 16550A, Port: 0x03f8, IRQ: 4
        Baud_base: 115200, close_delay: 50, divisor: 0
        closing_wait: 3000
        Flags: spd_normal skip_test

Terminalsoftware:


 sudo apt-get install minicom
 minicom -s # (start setup, because default is /dev/modem, which is not normally found)

If file exists...

Shell *


[ parameter FILE ]
OR
test parameter FILE

Where parameter can be any one of the following:

-e: Returns true value if file exists
-f: Return true value if file exists and regular file
-r: Return true value if file exists and is readable
-w: Return true value if file exists and is writable
-x: Return true value if file exists and is executable
-d: Return true value if exists and is a directory

[ -e /dev/dvb/adapter0/ca0 ] && rm /dev/dvb/adapter0/ca0
[ -f /etc/rc.local ] && echo "rc.local found" || echo "rc.local not found"

Printing - CUPS - PPD - LPR

Printing Lenny


Add:
 sudo lpadmin -p koeprinter -D "infoa tulostimesta" -E -v lpd://192.168.0.2/lp -P Brother_HL-1440.ppd
Print:
 lpr -P koeprinter koe.txt
Print raw (plt):
 lpr -P koeprinter -l koe.txt
Remove:
 sudo lpadmin -x koeprinter 
Show options (if PPD-file added):
 lpoptions -p koeprinter -l
Set options:
 lpoptions -p koeprinter -o PageSize=A4

Default LPD-port: 515
PPD-files: /etc/cups/ppd/
Configfile: /etc/cups/printers.conf and /etc/printcap
D-Link lpd-queue: lp
HP lpd-queue: raw1

Multiple IP:s, one network interface

Network Ubuntu 10.10 /etc/network/interfaces


auto eth0
iface eth0 inet dhcp

auto eth0:0
iface eth0:0 inet static
   address 192.168.2.10
   netmask 255.255.255.0

One MAC-address, dhcpd3

Network Xubuntu 10.10 /etc/dhcp3/dhcpd.conf


class "PS3" { match hardware; }
subclass "PS3" 1:00:1F:A7:AB:5B:FD;

ddns-update-style none;
default-lease-time 600;
max-lease-time 7200;
authoritative;
log-facility local7;
subnet 192.168.2.0 netmask 255.255.255.0 {
 option domain-name "example.org";
 option domain-name-servers 8.8.8.8, 8.8.4.4;
 pool {
  range 192.168.2.128 192.168.2.250;
  allow members of "PS3";
 }
 next-server 192.168.2.1;
 filename "kboot.conf";
 option routers 192.168.2.1;
}

Network Block Device - NBD

Linux Gentoo-PS3 -> Ubuntu 10.10


emerge python
emerge nbd

/etc/rc.conf


nbd-server 1043 /dev/sr0


sudo apt-get install nbd-client
sudo modprobe nbd
sudo nbd-client 192.168.2.129 1043 /dev/nbd0
sudo mount /dev/nbd0 /cdrom

Booting from network

Network Debian 5 (Lenny)


sudo apt-get install tftpd-hpa
sudo apt-get install dhcp3-server
sudo apt-get install nfs-kernel-server

/etc/default/tftpd-hpa -> RUN_DAEMON="yes" (verbose: -vvvvvv) /etc/dhcp3/dhcpd.conf


ddns-update-style none;
default-lease-time 600;
max-lease-time 7200;
authoritative;
log-facility local7;

subnet 192.168.2.0 netmask 255.255.255.0 {
 option domain-name "example.org";
 option domain-name-servers 192.168.2.50;
 pool {
  range 192.168.2.128 192.168.2.250;
 }
 next-server 192.168.2.50;
 filename "pxelinux.0";
 option routers 192.168.2.50;
}


cd /var/lib/tftpboot
wget http://http.us.debian.org/debian/dists/lenny/main/installer-i386/current/images/netboot/netboot.tar.gz
sudo tar xvfz netboot.tar.gz

Alsa to file

Sound Debian 6 (Squeeze) ~/.asoundrc


#pcm. !default filewrite
pcm.filewrite {
 type file
 slave {
  pcm "hw:Dummy"
 }
 file "| cat > /tmp/out_%r_%c_%b_%f_`date +%%s`.raw"
 perm 0777
 format "raw"
}

Test:


mpg123 -v -v -a filewrite -o alsa -r 48000 http://relay1.slayradio.org:8000
aplay /tmp/out_44100_2_16_S16_LE_1298980235.raw -r 44100 -f S16_LE -c 2

Handling Debian packages: apt-get/apt-file/dpkg

Debian Debian 6 (Squeeze)


See what files package installs
apt-file show PACKAGE

Search file from packages 
apt-file search FILE

See what files installed package includes
dpkg -L INSTALLED_PACKAGE

List installed packages
dpkg --get-selections

Install .deb-file
dpkg -i DEBFILE

Force remove dep
dpkg --remove --force-remove-reinstreq DEBFILE

Unpack .deb-file
ar vx DEBFILE
tar xvfz data.tar.gz
tar tvfz data.tar.gz (just view without decompress)
tar xvfz FILE data.tar.gz (extract single file)
tar --xz -xvf data.tar.xz (XZ compressed data)

Remove all but one:
ls *|grep -v FILENAME|xargs rm -rf

Delete all but following files

Shell Debian 6 (Squeeze)


ls | grep -v FILENAME1 | grep -v FILENAME2 | xargs rm -Rf

Compress and decompress initrd

Boot Debian 6 (Squeeze)


Decompress initrd:
 mkdir /tmp/initrd
 cd /tmp/initrd
 zcat initrd.img | cpio -i

Prepare and compress initrd:
 pushd .
 cd /tmp/initrd/lib/modules/2.6.37-1-686
 sudo depmod -b /tmp/initrd 2.6.37-1-686
 cd /tmp/initrd
 find . | cpio -o -H newc | gzip > /tmp/initrd.img
 popd

Qemu

Emulation Debian 6 (Squeeze)


qemu -kernel vmlinuz -initrd initrd.img -append "root=/dev/sda" -hda hdimage

Aptitude (apt-get) and compiling from sources

Debian Debian 5 (Lenny)


sudo apt-get source PACKAGE
cd /usr/local/src/PACKAGE
dpkg-buildpackage -rfakeroot -b
sudo dpkg -i ../PACKAGE.deb

Search opened and recently written files

Debian Debian 5 (Lenny)


sudo find / -mmin -5
sudo lsof

ccache

Compiling Debian 5 (Lenny) ~/.bashrc


export PATH=/usr/lib/ccache:$PATH

ncftp

Network Debian 5 (Lenny) ~/.bashrc


EDITOR="/bin/nano" ; export EDITOR


ncftp -u [username] [ftp://address]
edit [filename]

Use samba without authentication

Network Debian 6 (Squeeze) /etc/samba/smb.conf


[global]
guest account = kurkku
security = share
guest ok = yes
follow symlinks = yes
wide links = yes
unix extensions = no

Debian - compiling kernel

Kernel Debian 5 (Lenny)


apt-get install kernel-package ncurses-dev fakeroot wget bzip2
cd /usr/src
wget http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.37.4.tar.bz2
tar xvfj linux-2.6.37.4.tar.bz2
cd linux-2.6.37.4
cp [old/debian-config-file] .config
nano Makefile (extraversion)
[export CONCURRENCY_LEVEL=3] (multiple threads/cores)
make menuconfig
make-kpkg clean 
fakeroot make-kpkg --revision=custom.1.0 kernel_image
dpkg -i kernel-image-2.6.37.4_custom.1.0_i386.deb
update-initramfs -k 2.6.37.4 -c

Show processtree

Kernel Debian 5 (Lenny)


ps -ef --forest | less

Root password recovery

Authentication Debian 6 (Squeeze)


Solution 1:
 Kernel parameter in bootloader:
  init=/bin/sh or single

  mount -n -o remount,rw /
  mount -avt nonfs,noproc,nosmbfs
  cd /etc
  vi passwd
  vi shadow

Solution 2 (boot with emergency/bootdisk or other computer):
 mkdir recovery
 mount /dev/hda3 recovery
 cd recovery/etc
 vi shadow
 vi passwd

To disable the root password, edit the second data field in the password file so that it is empty.

Turn monitor off

Energy saving Debian 6 (Squeeze)


sudo apt-get install vbetool
vbetool dpms off

To Do:
-shell: du, df
-initrd: blacklist
-kernel: compile/packing/install
-boot: grub, configure/update
-shell: sed, replace string
-shell: find|grep
-shell: lsof
-shell: sensors
-network: bwm-ng
-network: alpine, mutt (smtp)
-shell: ccache
-shell: make -j2
-network: samba, fstab, iocharset (ISO-8859-1, UTF)
-network: samba, mount, iocharset (ISO-8859-1, UTF)
-shell: characterset conversion
-find illegal characters from filenames
-network: iptables/ipforward, NAT
-network: apache, redirect
-network: apache, password authentication
-linux: apt, backport
-network: open ports
-shell: file, ldconfig, ldd
-kernel: depmod
-shell: output redirect, error redirect
-boot: udev
-shell: chown, chmod
-linux: raid1
-shell: reset