*nix

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Revision as of 19:40, 20 July 2012 by Milk (talk | contribs) (→‎Security)
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Mainly linux, some unix-like.

  • Vim - Text editor, etc.
  • Git - Distributed version control
  • IRC - Internet Relat Chat
  • Bitlbee - IM

Guides

Dotfiles

System

Boot

File structure

ln -s {target-filename} {symbolic-filename}

Terminals

Basics

Urxvt

tabbed is good, plus tmux.

Screen

config goes in ~/.screenrc 

escape ^Ww
  change escape key to w

Tmux

  • tmux - terminal multiplexer

config goes in ~/.tmux.conf 

tmux lsc
  list clients

tmux detach-client -t /dev/pts/26
  remove other clients from session (if screensize is fucked)

Misc

Shell

Bash

man: echo

Basics
Options
More

Zsh

lshell

Other

Commands


  • auditd - userspace component to the Linux Auditing System [5]
  • nice - run a program with modified scheduling priority
  • cut - remove sections from each line of files
  • shelr - console screencasting tool

System

  • lsof - "lists open files" (lots, given "everything" is a file)

iostat, vmstat, free

Mount

mount -o remount /
  remount partition after /etc/fstab change

Users

  • /etc/passwd - local user information
    • account:password:UID:GID:GECOS:directory:shell
  • /etc/shadow - restricted access encrypted password file
useradd username
  create user with defaults (no password)
useradd -D
  show defaults that will be used

useradd -m -g [initial_group] -G [additional_groups] -s [login_shell] [username]
  -m - add home dir
  -d - non-default home dir path
  -c comment
  -e 2006-06-30 - expires
useradd -m -g users -G audio,lp,optical,storage,video,wheel,games,power,scanner -s /bin/bash username

adduser
  interactive tool

userdel username
  remove user
userdel -r username
  remove user plus their home folder, mail spool

cat /etc/passwd | cut -d: -f 1,3,6 | grep "[5-9][0-9][0-9]"
  List users on a system [6]

Groups

groupadd [group]
  add group
gpasswd -a [user] [group]
  add user to group
gpasswd -d [user] [group]
  delete user from group

User must relogin for new group to take effect.

Permissions

ACLs

Partition must have acl set in /etc/fstab (and be remounted after). 

setfacl -m "u:username:permissions"
setfacl -m "u:uid:permissions"
  add permissions for user

setfacl -m "g:groupname:permissions"
setfacl -m "g:gid:permissions"
  add permissions for group

setfacl -m "u:user:rwx" file
  add read, write, execure perms for user for file
setfacl -Rm "u:user:rw" /dir
  add recursive read, write perms for user for dir
setfacl -Rdm "u:user:rw" /dir
  add recursive read, write perms for user for dir and make them default for future changes

Finding files

find /usr/share -name README
find ~/Journalism -name '*.txt'
find ~/Programming -path '*/src/*.c'

find ~/Images/Screenshots -size +500k -iname '*.jpg'
find ~/Journalism -name '*.txt' -exec cat {} ;
find ~/Journalism -name '*.txt' -print0 | xargs -0 cat   (faster than above)

find / -group [group]
find / -user [user]

http://arstechnica.com/information-technology/2011/07/ask-ars-how-to-use-the-find-command-in-a-pipeline/

  • sgrep - search a file for a structured pattern

Moving files

scp 

scp -P 2264 foobar.txt your_username@remotehost.edu:/some/remote/directory
scp -rP 2264 folder your_username@remotehost.edu:/some/remote/directory

Viewing files

less is better than more 

cat filename
  output file to screen
cat -n filename
  output file to screen w/ line numbers
cat filename1 filename2
  output two files (concatinate)
cat filename1 > filename2
  overwrite filename2 with filename1
cat filename1 >> filename2
  append filename1 to filename2
cat filename{1,2} > filename2
  add filename1 and filename2 together into filename3

head filename
  top 10 lines of file
head -23 filename
  top 23 lines of file
tail filename
  bottom 10 lines of file
tail -23 filename
  bottom 23 lines of file

sed -n 20,30p filename
  print lines 20..30 of file [7]

Media

Package management

Apt

dpkg --get-selections > installed-software
  create list of installed software

dpkg --set-selections < installed-software
dselect
  reinstall from list

Pacman

pacman -Syu
  upgrade system
pacman -Qo [file]
  check what package owns a file
pacman -Qqtd
  check whether there are any orphaned packages
pacman -Rsn packagename
  remove orphaned packages
  • cacheclean - Cleans up pacman packages. Users selects how many old versions to keep.
cacheclean {-p} {-v} <# of copies to keep>
# of copies to keep - (required) how many generations of each package.
-p - (optional) preview what would be deleted.
-v - (optional) show deleted packages.

Compression

# Extract Files
extract() {
 if [ -f $1 ] ; then
     case $1 in
         *.tar.bz2)   tar xvjf $1    ;;
         *.tar.gz)    tar xvzf $1    ;;
         *.tar.xz)    tar xvJf $1    ;;
         *.bz2)       bunzip2 $1     ;;
         *.rar)       unrar x $1     ;;
         *.gz)        gunzip $1      ;;
         *.tar)       tar xvf $1     ;;
         *.tbz2)      tar xvjf $1    ;;
         *.tgz)       tar xvzf $1    ;;
         *.zip)       unzip $1       ;;
         *.Z)         uncompress $1  ;;
         *.7z)        7z x $1        ;;
         *.xz)        unxz $1        ;;
         *.exe)       cabextract $1  ;;
         *)           echo "\`$1': unrecognized file compression" ;;
     esac
 else
     echo "\`$1' is not a valid file"
 fi
}

z7 does autodetection?

Disk usage

du -sh
  size of a folder
du -S
  size of files in a folder

du -aB1m|awk '$1 >= 100'
  everything over 100Mb

cd / | sudo du -khs *
  show root folder size

sudo du -a --max-depth=1 /usr/lib | sort -n -r | head -n 20
  size of program folders /usr/lib

du -sk ./* | sort -nr | awk 'BEGIN{ pref[1]="K"; pref[2]="M"; pref[3]="G";} { |
total = total + $1; x = $1; y = 1; while( x > 1024 ) { x = (x + 1023)/1024; y++; } |
printf("%g%s\t%s\n",int(x*10)/10,pref[y],$2); } END { y = 1; while( total > 1024 ) |
{ total = (total + 1023)/1024; y++; } printf("Total: %g%s\n",int(total*10)/10,pref[y]); }'
  foooked?
  • ncdu - ncurses disk usage
ncdu / --exclude /home --exclude /media --exclude /run/media
  check everything apart from home and external drives

ncdu / --exclude /home --exclude /media --exclude /run/media
  check everything apart from external drives

todo; source aliases.zsh

Time

Convert unixtime into date; 

date -d @1337000000

ntpdate pool.ntp.org && hwclock --systohc && hwclock --adjust
  Synchronize both your system clock and hardware clock and calculate/adjust time drift.
  Do not run this command if you already have ntpd running! [9]

Logs

GUI

X

Window Managers

Openbox

Qt

qtconfig qt4

Distros

Arch

Debian

Ubuntu

CentOS

Red Hat Enterprise Linux (RHEL)

"Red Hat Enterprise Linux is available only through a paid subscription service that provides access to software updates and varying levels of technical support."

"Since Red Hat Enterprise Linux is based completely on free and open source software, Red Hat makes available the complete source code to its enterprise distribution through its FTP site to anybody who wants it. Accordingly, several groups have taken this source code and compiled their own versions of Red Hat Enterprise Linux, typically with the only changes being the removal of any references to Red Hat's trademarks and pointing the update systems to non-Red Hat servers. Groups which have undertaken this include CentOS (the 8th most popular Linux distribution as of November 2011), Oracle Linux, Scientific Linux, White Box Enterprise Linux, StartCom Enterprise Linux, Pie Box Enterprise Linux, X/OS, Lineox, and Bull's XBAS for high-performance computing. All provide a free mechanism for applying updates without paying a service fee to the distributor.""

If going down the based-on-RHEL route, consideration needs to be paid towards the update delay of the distros when a new RHEL release comes out.

Oracle Linux

Quicker to release, but the corperate atmosphere of Oracle has a baaad relationship with the open source world in general (Java lawsuits, etc). [10]

Scientific Linux (SL)

Other software

CUPS

Printing system.

Regex

Networking

  • sudo /etc/init.d/<service> restart - ubuntu, restart a service
  • sudo /etc/rc.d/<service> stop | start | restart - arch, service things
  • sudo sh -c "echo 'something' >> /etc/privilegedfile"
  • chown -R user:group . - change all and subitems [11]
  • route -n - display the host's networks and gateway
  • View The Daily Show, etc. in the UK, etc. Mofity HTTP headers; X-Forwarded-For "12.13.14.15" [13]

Cisco

Media

To check;

Storage

VOIP

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