bits of knowledge of sysadmin

cat .ssh/id_rsa.pub | ssh 111.122.1.98 "cd;mkdir .ssh;cat >> .ssh/authorized_keys; chmod 600 .ssh/authorized_keys"

2010-09-20T04:38:00.001+10:00

find . -type f -print0|xargs -0 ls -s1|sort -rn|head

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tr -cs "[:alpha:]" "\n" < bool2.pl |tail -10

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modprobe -r pcspkr ---switch off pc speaker

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vim: %&g --repeat last substitution everywhere in the file

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dmesg|dd -conv ucase

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vim: :s ---repeat last substitution. Or simply &

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tar cf - old-dir |(cd new-dir; cd ..; tar xvpf -)

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vim: :%s/Intel/\U&/gc

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vi: %s/^=.*=/=&=/gc ----lowers all headers level in wikipedia by one.

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ex: 3,8s/.*/(&)

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tar xvf my.tar `tar tf my.tar|grep 'pattern';sleep 60`

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:%s/\(abcd)\1/alphabet-soup/ ----changes 'abcdabcd' into 'alphabet-soup'

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ex: :s/End.*/End ---removes all characters on the line after 'End'

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cd; find . -print|tar cvf /dev/rmt/0cbn -T -

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vim: :g/3/s/line/LINE/gc ---on lines containing '3' substitute 'line' by 'LINE'

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screen -D -R

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cat /proc/cmdline ---shows parameteres passed to the kernel during boot

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man 7 signal

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ex: 164,220 ya a ---yank lines 164 through 220 into buffer a. pu a ----put buffer a.

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vim: % refers to the current filename, # - to the alternate filename. :w %.new ^^

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vim: :e! ---discard edits and return to the saved version of the current file.

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find . -print|cpio -oacvB|(ssh myhost dd of=backup.file bs=5120

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dmesg|grep cpu. -io

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vim: :args :last :rewind

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dpkg -iG foo ---G says not to proceed if a newer package is already installed.

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ext: tune2fs -l /dev/hda2

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vim: :0r foo.txt :$r foo.txt :$185 foo.txt :/pattern/r foo.txt ---place contents of foo.txt in the beggining, end, after line 185 or after first linke with 'pattern' accordingly.

2010-02-02T13:23:00.000+11:00

`usermod -L` locks the user, `usermod -U` unlocks

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gpg --keyserver=x-hkp://pgp.mit.edu --send-keys e4eac24b

2010-01-20T16:55:00.000+11:00

df . ---quickly determine what filesystem the current directory is in.

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virtualization-capable CPU (/proc/cpuinfo) must have a flag SVM (for AMD) or VMX (for Intel)

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etherpad.com

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ex: g/pattern1 ---print all lines containing pattern1

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ex: /pattern1/;+5 ---print the first line containing pattern1 and 5 lines following it.

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audit2allow -i /var/log/audit/audit.log

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chcon -R -t httpd_user_content_t /var/www/

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yum install postfix system-switch-mail

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ex: 5,+5 --prints lines 5 through to current line +5. It can cause an error if the current line has a number less than the first line in range. 5;+5 with ; instead of , makes the end relative. ie it will be calculated from the first line of range.

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ex: /foo/,/bar/d ---delete lines starting with the first occurance of foo through to the nex occurance of bar

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ex: /gaga/+d ---delete a line below the first line containing 'gaga'. It is the same as /gaga/+1d

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IPADDR_START ..

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/etc/sysconfig/network-scripts/ifcfg-eth0-range0
IPADDR_START=192.168.0.100
IPADDR_END=192.168.0.200
CLONENUM_START=1 ---it can be any number. The devices will be numbered starting from it, e.g. if CLONENUM_START=5, then the first will be eth0:5.

~/.bash_profile: export EDITOR=vim; export VISUAL=vim; export PAGER=LESS

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expand -i -t 18

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ex: ,/gaga/d ---delete current line through to the next line containing 'gaga'

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ex: /gaga/d ---delete next line containing gaga

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ex: -,+t0 ---copy three lines (the line above the cursor through the line below the cursor) and put them at the top of the file.

2009-12-07T21:31:00.002+11:00

mke2fs -t ext4 -O ^has_journal /dev/sdf -L sysrescuecd

2009-12-07T14:10:00.001+11:00

grub-install --root-directory=/media/usbstick/ /dev/sdf

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touch /forcefsck or `shutdown -rF now` ---the -F option forces fsck on reboot

2009-12-05T00:54:00.001+11:00

no sound in skype with pulseaudio: pavucontrol

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ex: ,+5# ---shows line numbers of 5 lines starting from the current one, ,+ 5# --with a space between + and the number, shows file numbers of current AND 5 following lines, i.e. 6 lines in total; +5# ---without comma in front, is not a range and will operate on exatly one line, the fifth from the current one

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ex: .,+203# or ,+203 (dot can be ommitted, because it is presumed when + is used) --display line numbers from the current line to 203 lines further

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ex: 500,$m.-2 ---move lines from 500 through the end of the file to two lines above the current line

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httpd.conf: AddOutputFilterByType DEFLATE text/html text/plain text/xml text/css application/javascript application/x-javascript ---enables compression ..

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http://www.gidnetwork.com/tools/gzip-test.php

service httpd configtest

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yum.conf: metadata_expire=90m

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rpmbuild --showrc

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ex: .,.+32d ----delete 32 lines starting from the current one

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syslogd -a /var/named/chroot/dev/log

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man bootparam

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man capabilities

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dnssec-keygen -a hmac-md5 -b 256 -n USER dyndns --> in the global part of named.conf add key dyndns { algorithm HMAC-MD5; secret "Qoeuoaeu";}; --> for each zone that you want to have dynamic updates write 'allow-update {key dyndns; };'

2009-12-01T13:23:00.000+11:00

xsetroot -solid black

2009-11-30T21:52:00.002+11:00

rpm --checksig; rpm -K

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dhcpd.conf: shared-network {subnet {group { host }}}}

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ex: %d ---delete all lines in a file

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ex: 23,.m$ --move lines from 23 to the current line to the end of the file

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pinfo

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man -aw ls

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man -d ls

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when you get segmentation fault in yum: rm -f /var/lib/rpm/__db*; rpm --rebuilddb

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xorg.conf is missing: Xorg -configure :1

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ex: := prints the total number of lines; :.= prints the line number of the current line.

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ex: 1,10# --display lines 1 to 10 and their respective numbers; se nu; se nonu

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for i in {0..110};do echo line $i;done

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`xmonad --recompile` ---same as alt-q when xmonad is running, but does not require even X11 to be running.

2009-11-27T15:56:00.000+11:00

prevent overwrite of existing files: set -o noclobber; disable with `set +o noclobber`

2009-11-27T13:15:00.002+11:00

dd if=8.0-RELEASE-amd64-memstick.img of=/dev/da0 bs=10240 conv=sync

2009-11-27T13:10:00.001+11:00

tcpdump -i any

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fedora installation mounts: /mnt/sysimage; /mnt/isodir

2009-11-25T16:21:00.002+11:00

nt: fsutil file createnew swap_device 536870912

2009-11-25T12:52:00.002+11:00

distro upgrade: apt-get dist-upgrade; fedora: preupgrade

2009-11-25T12:35:00.000+11:00

bash: repeat a command that contained foo ANYWHERE in the line: !?foo; repeat a command that contained foo IN THE BEGINNING of a line : !foo; ^ma^pa executes THE LAST command replacing FIRST occurance of 'ma' with 'pa'

2009-11-24T12:35:00.000+11:00

.bashrc: HISTFILE="~/.bash_history; HISTSIZE=10000

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yum groupinstall "Moblin Desktop Environment"

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vim: "1pu.u.u.u

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winecfg; wine control; winefile; wine uninstaller; wine foo.exe

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ports: dhcpd listens on UDP:67 and answers using UDP:68

2009-11-23T21:32:00.000+11:00

screen /dev/ttyS0

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use output of one command as an argument of another: rm -i $(find -iname *.mp3)

2009-11-23T21:22:00.001+11:00

reboot system every time user connects to the system. The user will not be able to run any commands. ~/.ssh/authorized_keys: no-port-forwarding,command="/sbin/reboot",no-pty ssh-rsa AB...YZ

2009-11-23T21:14:00.000+11:00

yum install yum-presto

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grep 'a b' 44 ..

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user@system3:/tmp$grep 'a
> b' 44
aa bb
aabb
user@system3:/tmp$grep 'ab' 44
aabb
user@system3:/tmp$grep 'a b' 44
aa bb
user@system3:/tmp$sudo -i^C
user@system3:/tmp$cat 44
aa bb
aabb

open file on the last line: vim + /var/log/messages; less +G /var/log/messages

2009-11-23T15:41:00.002+11:00

mysql_install_db --user=mysql; mysql_secure_installation

2009-11-23T13:39:00.001+11:00

Things to take with when going out:

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Contact Phone numbers, address and map, keys or whatever is required to get in
Warm jacket
Rescuecd, rescueusb
Laptop with tftpd, dhcpd
3g modem
Cable cat5 cross
cable com-to-usb
Screwdriver
RSA keys
presents
more business cards than usual
phone friends to tell you will be around

chkconfig nscd on; nscd -i hosts; ipconfig /flushdns

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for i in {1..19}; do echo $i; done

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PS1="\u@\h:\w\$"

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