Welcome to Unix

1
Welcome to Unix

• Crafted by the CSUA at Berkeley
• http//csua.berkeley.edu
• Presented 8/29/2002

2
Redistribution

• The authors (nor anyone else) provides no
  warranty or claim of accuracy of this document.
  Use at your own risk.
• You may use this document in whole or part
  according to the terms of the GPL. See
  http//www.gnu.org/copyleft/gpl.html for details.

3
Outline

• I. getting help
• II. the file system
• III. the shell
• IV. safe computer sex
• V. email options
• VI. and lesser editors
• VII. input and output redirection
• VIII.printing
• IX. process management
• X. X

4
What is it and where do you get it?

• An operating system used on everything from
  servers to embedded systems.
• To you, probably a prompt
• gt type stuff here
• You get a temporary account when you take a CS
  class. Get a (more) permanent account from the
  OCF or CSUA. Or buy a Mac.

5
If you know only one thing, know how to RTFM.

• gtman command
• gives you help on that command.
• gtapropos keyword
• tells you all man pages that contain keyword.

6
How to get help.

• Come to the CSUA office, 343 Soda.
• HKN is next door the CSUA.
• Go to the OCF in the MLK Heller Lounge when
  someone is holding staff hours.
• Post your question to a newsgroup (like your
  class newsgroup).
• Hit the man pages/web first !

7
Outline

• I. getting help
• II. the file system
• III. the shell
• IV. safe computer sex
• V. email options
• VI. and lesser editors
• VII. input and output redirection
• VIII.printing
• IX. process management
• X. X

8
Files and DirectoriesNaming something gives you
power over it.
9
Absolute Addressing
10
Addressing relative to your home dir.
11
Addressing relative to your current dir.
12
File system commands

• pwd - report your current directory
• cd ltto wheregt - change your current directory
• ls ltdirectorygt -list contents of directory
• cp ltold filegt ltnew filegt - copy
• mv ltold filegt ltnew filegt - move (or rename)
• rm ltfilegt -delete a file
• mkdir ltnew directory namegt -make a directory
• rmdir ltdirectorygt -remove an empty directory

13
getting recursive

• remove a directory and its contents
• rm -r ltdirectorygt
• copy a directory and its contents
• cp -r ltdirectorygt

14
File permissions.

• There are 3 kinds of people in the world you
  (user), your friends (group) and everyone else
  (other).
• Each sort of person may or may not be able to
  read, write, or execute a file.
• gtls -l .forward
• -rw-r--r-- 1 darin csua 23 Jan 23 2002
  .forward
• gtls -l .cshrc.local
• -rwxr-xr-- 1 darin csua 2988 May 19 0048
  .cshrc.local

15
executing

• executing a file means running it as a program.
• executing a directory means setting your
  current directory to it using cd.

16
Changing File Permissions

• make a file readable to your friends
• chmod gr ltfilenamegt
• change who owns a file
• chown ltusergt ltfilenamegt
• change to which group the file belongs
• chgrp ltgroupgt ltfilenamegt

17
touch

• look at the full listing again
• gtls -l .forward
• -rw-r--r-- 1 darin csua 23 Jan 23 2002
  .forward
• Each file has a date stamp of when it was
  modified.
• Use touch to set the timestamp to the current
  clock.
• touch ltfilenamegt
• Touch creates the file if it didnt exist
  beforehand.
• You can only touch a file to which you can write.

18
Symbolic Links

• use ln -s ltold filegt ltsecond namegt to create a
  symbolic link to a file.
• gtls -l .forward
• -rw-r--r-- 1 darin csua .forward
• lrwxr-xr-x 1 darin csua .forward.link_at_ -gt
  .forward
• The first l tells you that its a symbolic
  link.
• Symbolic links can be used as if it were its
  target.

19
Outline

• I. getting help
• II. the file system
• III. the shell
• IV. safe computer sex
• V. email options
• VI. and lesser editors
• VII. input and output redirection
• VIII.printing
• IX. process management
• X. X

20
whats a shell?

• The shell is the program that
• runs when you log in. It prints
• the prompt and reads what you
• type, invokes programs, etc.
• your window to the Unix world.
• use chsh ltnew shellgt to change your shell

21
File Globbing

• some commands can work on many files at once
• gt rm file1 file2 file27
• Use to match any number of unknown characters
• gt rm file
• Use ? to match one unknown character.
• gt rm file?

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(un)aliasing

• create shortcuts for yourself
• gtalias ll ls -la
• Use alias with no arguments to discover current
  aliases
• gtalias
• rm rm -i
• ll ls -la
• Type unalias rm to remove alias.

23
shell variables, echo

• (tcsh) gtsetenv BOB joe
• (tcsh) gtprintenv BOB
• joe
• (tcsh) gtecho BOB
• joe

24
PATH a very important shell variable

• gtecho PATH
• /home/d/da/darin/bin/opt/local/bin/opt/local/bin
  /pbmutils/usr/bin/usr/sbin/opt/SUNWspro/bin/us
  r/ccs/bin/opt/local/X11/bin/usr/dt/bin/usr/open
  win/bin/opt/local/gnu/bin/opt/local/games/bin/u
  sr/ucb./
• If a program (like ls) is in one directory found
  in your path, then typing it (gtls ltentergt) will
  execute it.
• Otherwise you can type the full absolute address
  to execute a program (gt/usr/bin/ls ltentergt)

25
finding things in your PATH.

• Type which ltcommandgt to find the location of
  the program which would be run when you type
  ltcommandgt.
• If you dont remember if it was chgrp or chgroup,
  type chltcontrol-dgt to get a list of commands
  that starts with ch.
• when all else fails, use find to find a file.
• gtfind ltstart dirgt -name .doc

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Other useful pre-defined shell variables

• HOST what computer youre logged into
• PAGER program used display man pages
• PWD current directory
• GROUP what group youre in
• USER your login

27
Shell scripts.

• If you have a bunch of commands youd like to
  automate, you can put them on separate lines of a
  file. Then type source ltfilegt to run the
  script.
• If the first line of your script looks like
• !ltprogram namegt
• then you can make the script executable. When it
  executes, it uses ltprogram namegt to interpret the
  contents of the script.

28
Login scripts

• Most people have a script that executes when they
  log in. It is commonly used to set up ones PATH
  and aliases.
• Ask someone to help you start your own login
  script.

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screen is your friend

• You can use the program screen to run several
  shells from one window.
• create a new shell by pressing ltctrl-agt c
• switch shells by pressing ltctrl-agt ltnumbergt
• use ltctrl-agt d to detach a session and come
  back to it later.

30
Outline

• I. getting help
• II. the file system
• III. the shell
• IV. safe computer sex
• V. email options
• VI. and lesser editors
• VII. input and output redirection
• VIII.printing
• IX. process management
• X. X

31
Your Options

• Abstinence
• (switch majors, unplug your computer)
• monogamy
• (use only one computer, do not use network)
• protection
• (also known as encryption)

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What not to use.

• telnet, ftp, rlogin
• all your data (including your password) is
  transmitted plain text over the network.
• from library machines you can use the java ssh
  client from a web browser.

33
using ssh keys

• use ssh-keygen to generate a public/private set
  of keys. You keep the private key and append the
  public key to authorized_keys.
• You can now log in using either your password or
  the private key file.

34
using secure copy scp

• copy local to remote
• scp ltsource filegt user_at_machineltpathgt
• copy remote to local
• scp user_at_machineltpathgt ltsource filegt

35
Outline

• I. getting help
• II. the file system
• III. the shell
• IV. safe computer sex
• V. email options
• VI. and lesser editors
• VII. input and output redirection
• VIII.printing
• IX. process management
• X. X

36
the program mail

• mail useful for sending
• gtmail darin_at_csua
• Subject hello
• Cc
• hi there
• this is a message
• .

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other console based options

• elm - quick and simple, easy to use, but doesnt
  handle attachments very well.
• pine - more complete. the standard
• mutt - most modern/complex.

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accessing mail remotely

• netscape, outlook, eudora, and others can get at
  your mail using POP or IMAP.
• POP takes the messages off the server to your
  local computer.
• IMAP only reads headers, but leaves mail how it
  is on the server. Works well if you wish to use
  console based email.
• ALWAYS use SSL (encryption).

39
Outline

• I. getting help
• II. the file system
• III. the shell
• IV. safe computer sex
• V. email options
• VI. and lesser editors
• VII. input and output redirection
• VIII.printing
• IX. process management
• X. X

40
vi

• is an editor available on all decent Unix
  systems. Developed at Berkeley.
• Has two modes command and insert. In insert
  mode you can type normally.
• Press escape to get into command mode. In
  command mode each letter is a command.
• hjkl ? ????

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pico - the pine composer

• the simplest visual editor available on most Unix
  systems.
• all possible commands displayed at bottom of
  screen. (control-somethings)
• no real surprises

42
emacs

• Always has one major mode running, potentially
  several minor modes.
• stands for editing macros - designed by and for
  lisp programmers.

43
Outline

• I. getting help
• II. the file system
• III. the shell
• IV. safe computer sex
• V. email options
• VI. and lesser editors
• VII. input and output redirection
• VIII.printing
• IX. process management
• X. X

44
STD

• All terminal programs have
• standard output, which is usually your screen
• standard input, which is usually your keyboard
• standard error, which is also the screen

45
redirect output to a file with gt

• If you type who at the prompt, you will get a
  list of who is logged into the system.
• If you type who gtf, a file named f will be
  created and the standard output of who will be
  placed in that file instead of to your screen.

46
gt vers gtgt

• By default, who gtf will overwrite the file f.
• Use who gtgtf to append to f rather than
  overwriting it.

47
redirecting input from a file with lt

• The program sort will sort its standard input and
  then print it on standard out.
• To sort the lines of file1 and display
• sort lt file1
• To sort the lines of file1 and save in file2
• sort lt file1 gt file2

48
The output of one program can be the input to
another.

• who sort
• The output of who is sorted and shown on your
  terminal screen.

49
grep

• grep shows only those lines containing its search
  pattern.
• To see all lines in a file containing bob
• grep bob lt file1

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The cat command

• the arguments to cat are concatenated together
  and displayed on stdout. To view a file
• cat file1
• if no arguments, cat puts on stdout whatever you
  type on stdin, so this does the same thing
• cat lt file1

51
Outline

• I. getting help
• II. the file system
• III. the shell
• IV. safe computer sex
• V. email options
• VI. and lesser editors
• VII. input and output redirection
• VIII.printing
• IX. process management
• X. X

52
printers have stupid names

• The printers downstairs are named lw274.
• The printer in 330 is called lw330.

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how to print a .ps file

• syntax
• lp -Dltprintergt ltfilenamegt
• example
• lp -Dlw330 myfile.ps

54
how to print a .pdf file

• convert it to .ps first!!!
• use the pdf2ps utility program.
• pdf2ps input.pdf output.ps

55
how to print other file types

• Convert them to .ps first!!!
• The program a2ps (anything to .ps) works most of
  the time.

56
How to check the printers queue.

• syntax
• lpq -Pltprinter_namegt
• example
• lpq -Plw330

57
How to cancel your print job.

• Type cancel.

58
Outline

• I. getting help
• II. the file system
• III. the shell
• IV. safe computer sex
• V. email options
• VI. and lesser editors
• VII. input and output redirection
• VIII.printing
• IX. process management
• X. X

59
To start a process in the background, use .

• example
• big_program gt output
• big_program will not have input!

60
managing jobs

• To suspend the currently active program, use
  ltcontrol-zgt.
• To return to the program you just suspended, type
  fg
• To put the program you just suspended in the
  background, type bg

61
To see a list of your programs running, type ps.

• gtps
• PID TTY TIME CMD
• 866 pts/1 000000 tcsh
• 872 pts/1 000000 ps

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use kill to end a process

• gtps
• PID TTY TIME CMD
• 866 pts/1 000000 tcsh
• 874 pts/1 000000 cat
• 875 pts/1 000000 ps
• gtkill 874
• 1 Terminated cat

63
kill -9

• If kill ltPIDgt doesnt end your process, use
  kill -9 ltPIDgt

64
Outline

• I. getting help
• II. the file system
• III. the shell
• IV. safe computer sex
• V. email options
• VI. and lesser editors
• VII. input and output redirection
• VIII.printing
• IX. process management
• X. X

65
cutting and pasting

• Highlight some text in any window.
• Hit the middle mouse button in another window.
• The highlighted text appears.
• There is no saving to the clipboard step as in
  Microsofts Windows or MacOS.

66
Changing your fonts.

• ltcontrol-leftclickgt in xterm
• edit --gtpreferences --gt fonts in netscape.

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Changing your window manager.

• Your /.xsession gets run when you log into X
  windows, the last line sets which window manager
  you are going to use.
• You probably want someone to set up your X
  configuration for you the first time.

68
Using X windows at home on a MS-Windows machine.

• You need to get a program called a program called
  an Xserver. Exceed works well and is free for
  academic use.
• You must allow X-forwarding through your ssh
  client. Putty is good for this.

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