Unix

Two of the most famous products of Berkeley are LSD and Unix, I don't think that this is a coincidence.

Unix Design Goals and the "Unix Philosphy"

• Designed for programmers by programmers.
  • No excess documentation and warnings.
  • The source code is the documentation.
• Small, simple, single purpose programs are best.
• Simple programs in a pipeline can perform complex tasks.
  • All files are just byte streams.
  • Output from one program can be passed as input to another.

Terminals and Keyboards

Unix supports a wide variety of terminals (and teletype devices). Due to the wide variation in early keyboards, basic editing features were implemented consistently with ordinary characters which were guaranteed to be on all terminals. The major editing functions were implemented so that they could be changed to match specific terminal features after login, but the original settings are still used during login on HP-UX.


• stty - command to set/show teletype device options
• $TERM - a shell variable containing the terminal type

Function	Original Key	Modern Key
Erase (Character)	#	BS (Ctrl-H) or DEL (ASCII 127)
Kill (erase line)	@	NAK (Ctrl-U)
EOF (end of file)	EOT (Ctrl-D)	EOT (Ctrl-D)
Intr (interrupt process)	DEL	ETX (Ctrl-C)
Quit (stop process)		FS (Ctrl-\)
Swtch (send to background)		SUB (Ctrl-Z)

The Legacy of Manual Typewriters        

Original Problem:	People type too quickly and jam typewriters.
Original Solution:	QWERTY keyboards designed to prevent jams.
Second Problem:	Typing slow and difficult for Unix developers.
Second Solution:	Unix commands short (abbreviated) to reduce typing.
Lesson (Not) Learned:	Design choices during the early stages of product development have a profound impact throughout its lifetime and even affect future products.

Shells

• sh - Bourne shell (orginal)
• csh - C shell (BSD)
• ksh - Korn shell (SysV)
• bash - Born (Bourne) Again shell (FSF)
• zsh, tcsh, ... - enhancements of earlier shells

Command Format

• command name
• options / switches
• arguments / parameters

FALCON} date
Mon Apr  5 14:37:00 EDT 1999

FALCON} date -u
Mon Apr  5 18:37:07 UTC 1999

FALCON} cal
   April 1999
 S  M Tu  W Th  F  S
             1  2  3
 4  5  6  7  8  9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
25 26 27 28 29 30

FALCON} cal 9 1752
   September 1752
 S  M Tu  W Th  F  S
       1  2 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30

Resource & Process Management

• Forground/Background
• Jobs - user processes
• Daemons - system processes

Load averages: 0.50, 0.43, 0.36         149 processes: 148 sleeping, 1 running

Cpu States:    LOAD   USER   NICE    SYS   IDLE  BLOCK  SWAIT   INTR   SSYS
               0.50   1.6%   0.0%   1.0%  97.4%   0.0%   0.0%   0.0%   0.0%

Memory:   39488K (31796K) real, 69784K (52328K) virtual, 18688K free  Page# 1/14

  TTY   PID USERNAME PRI NI   SIZE    RES STATE    TIME %WCPU  %CPU COMMAND
pts/3 14057 cooleycd 178 20  3380K   352K run      0:00  1.79  1.03 top
rroot 27152 schenksj 168 24   792K   112K sleep   98:05  0.70  0.70 java
rroot 12438 httpd    154 20  5452K  2476K sleep    1:12  0.42  0.42 ns-httpd
ttyp2 11300 kirschsb 154 20   408K   308K sleep    0:10  0.36  0.36 slirp
rroot     3 root     128 20     0K     0K sleep   30:30  0.14  0.14 statdaemon
rroot   679 ora73    156 20  8824K   116K sleep    0:38  0.07  0.07 ora_dbwr_ACAD

File Management

• Each disk has a File System
• Unix has a single Directory Tree
• Mount disks onto mount points (directories) in the tree

FALCON} bdf
Filesystem          kbytes    used   avail %used Mounted on
/dev/vg00/lvol3     223317  177022   23963   88% /
/dev/vg00/lvol1      47829   14341   28705   33% /stand
/dev/vg11/lvol2    1012557  730625  180676   80% /work
/dev/vg01/lvol3    1009705  595773  312961   66% /var
/dev/vg01/lvol2     512499  353904  107345   77% /usr
/dev/vg11/lvol3     303645  254894   18386   93% /usr/local
/dev/vg03/u04      2035601  197002 1635038   11% /u04
/dev/vg04/u03      2035601 1115944  716096   61% /u03
/dev/vg05/u02      2035601  478190 1353850   26% /u02
/dev/vg06/u01      2035601 1170989  661051   64% /u01
/dev/vg00/lvol4     984928    7280  879155    1% /tmp
/dev/vg01/lvol1     512499  440960   20289   96% /opt
/dev/vg10/lvol3     512499  318449  142800   69% /ops
/dev/vg11/lvol1     303645  194901   78379   71% /jmu
/dev/vg12/lvol12   2035601  982167  951653   51% /home2
/dev/vg02/home1    2034506 1451308  379747   79% /home1

File Management

• Current Working Directory
• Absolute & Relative Path Names
• Wild Card characters * ? [ ]
• Leading Dot

File Management - Access & Security

  drwxrwxr-x 3 root bin             1024 Jan 20 16:46 usr
	directory owned by root in the bin group
	read, write and execute by root user and members of bin group
	read and execute but no write by everyone else

  -rw-r----- 1 cooleycd users       2357 Dec 23 22:46 schedule.html
      a (data) file owned by cooleycd in the users group
      read and write access by user cooleycd,
      read access by members of group users, no access by others

  -rwxr--r-x 1 root bin            12288 Jun 10  1996 yes
      a (program) file owned by root in the bin group
      full access by the root user and read and execute by everyone else
      except those in the bin group who only get read access

Redirection and Pipelines

who > who.lst

less < who.lst

grep `whoami` /etc/passwd | cut -d: -f5

ps -ef | less

zcat /usr/man/man1.Z/ls.1 | nroff -man | more

who | wc -l

cut -d: -f6 /etc/passwd | grep home[12] |  
	cut -c2-6 | sort |  uniq -c | sort -n -r

Misc. Commands

• date - show current date and time
• cal - show a calendar
• dc - desk calculator

• who - show current system users
• whoami - show current userid

• man - view online manual pages
• echo - print a message on the screen
• passwd - change your password
• exit - exit from the shell (logout of system)

• w - show system info
• top - show system resource usage
• ps - show list of processes
• kill - send a signal (default signal is kill)
• jobs - show your background jobs

• mount - mount a disk into the file system tree
• umount - remove a disk from the tree
• df - show disk space (used, free, and total) of disks (bdf on falcon)
• du - show disk space used by directories and files

• ls - list files in a directory
• pwd - print working directory

• cd - change (current/working) directory
• mkdir - make a directory
• rmdir - remove a directory

• cp - copy a file
• mv - move a file (or rename)
• rm - remove a file
• touch - create a file

• file - attempt to determine the type of file
• cat - concatenate files (used to view)
• pg - view a file one page at a time (SysV)
• more - view a file one page at a time (BSD)
• less - view a files one page at a time (FSF)
• head - view the top lines in a file
• tail - view the last lines in a file

• ed - original AT&T editor
• ex - Berkeley's extensible editor
• vi - visual interface (to ex editor)
• emacs - editor from FSF
• pico - Pine Composer (from U. of Washington mail client)

• ls -l   - displays file details
• chown - change file owner
• chmod - change file modifiers (permissions)

• lp - line printer (SysV)
• lpr - line printer (BSD)

• pr - print (format page for printing)
• wc - word count (counts characters and lines too)
• sort - sort the lines of the file
• cut - pull a column of information from a file
• strings - extracts human readable strings from a file
• diff - show how two files are different

• find - locate files (a very un-Unix like command)

• tar - tape archive (used for backups)
• cpio - copy in/out (used for backups)

• sed - stream editor (used for programming tasks)
• awk - a programing language (authors' initials)
• grep - global regular expression print (searches for text in a file)