Unix Ramblings

Random Unix Ramblings

Bill C. MillerAllPlayers.com eat-n-geek

7/26/12

● GE / Bell Labs / MIT joined together on Multics project way back in 1965 (MAC - Multiple Access Computers project)○ simultaneous computer access to large

community (1st time share)○ easy data sharing between users

● AT&T/ Bell Labs says enough we are stopping multics project it failed (1969)

● Multics later finished in 1972

Very Brief History of Unix...

● Ken Thompson/Dennis Ritchie work on it on their own as they needed on OS for a PDP-7 to play space travel game

● The result was system which a punning colleague called UNICS (UNiplexed Information and Computing Service) -- an 'emasculated Multics'; soon changed to UNIX

Very Brief History of Unix...

● Designed to be small and simple OS

● 1st written on PDP-7 in 1969, then PDP-11 on 1970

● 1973, Ritchie and Thompson rewrote kernel in C as 1st portable operating system (hardware independent)

UNIX Created

● ATT (BTL) UNIX● BSD UNIX - ATT gave source code to

universities since not in computer business, and was picked up by Berkley forking to BSD 1977

● SUNos from BSD as well as openbsd, netbsd, next, macos

● Xenix - MS's UNIX, later by SCO● ATT goes commercial system V - 1979● Posix standard to get best of BSD and V● Linux

Flavors of *nix

ON being told most of the code being written for multics was for error recovery

Ritchie -- "We left all that stuff out. If there's an error, we have this routine called panic, and when it is called, the machine crashes, and you holler down the hall, "Hey, reboot it"

Error Code.. bah hum bug...

● Ken Thompson - b, fortran,ed, sort,grep,uniq, plot,dd,..

● Dennis Ritchie - C, fork-exec,db,ed, fortran

● Steve Bourne - bourne shell (sh), adb,..● Bill Joy - BSD UNIX, vi, csh, and founder

of SUN micro, adding TCP/IP to BSD..● Brian Kernigham - name UNIX, awk, troff,

eqn,..

UNIX Hall of Fame

● David Korn - Korn shell,..● Richard Stallman -- FSF, emacs, GNU,..● Brian Fox - bash shell while at FSF,

emacs maintainer, GNU tools● Linus Torvalds -- LINUX using GNU tools

UNIX Hall of Fame

2 - Tools/APPS -- commands and programs -- applications, programs1 - SHell -- interprets commands, executes programs, and internal commands -- system calls, libraries0 - Kernel -- schedules tasks and manages storage and devices -- Hardware

UNIX NUT

● Multi-user● Multi-tasking● Portable (hardware independent)● Extensible (easy to add to scripts,

commands, ...)● Robust (rare crashing, permissions,

simple filesystem used for files,disks, devices, pipes,...)

● Tools (many from the early days to years and years of contributed tools) -- modular

The Power of UNIX

● disk's, directory -- all the same to a user, and easy to mount a disk anywhere

● easy to navigate hierarchical file system and links

● file system i/o, is all the same regardless if a file, device, network stream, pipe, stdin (fd = 0) ,stdout (fd = 1) , stderr (fd =2), - , /dev/null○ all progs have access to stdin/stdout/stderr

The Power of UNIX

● # -- comment● ; -- chain commands● \ -- extend a line or quote char● < > -- redirect input , output● << >> -- redirect append input , output| -- pipe output● ` -- run command and place output as ..● " -- quote input as a unit● ' -- quote without variable replace

Some special chars

● & -- run command in background● ? , *, [a-z] char matching..● ~ , users home dir shortcut● cat file >afile 2>&1 (stderr to stdout)

○ but not cat file 2>&1 >afile● .....

Some special chars

● ^o - flush● ^s - stop● ^q - start● ^z- background (&, fg, bg, and %#)● ^c - interrupt● ^u - kill● ^d - end input● ^\ - terminate with core file● ......

Some Terminal Control Chars

● used emacs bindings on linux unless exported env for VISUAL or EDITOR

● ^a - front of line, ESC-a (sentence)● ^e - end of line, ESC-e (sentence)● ^k - kill line● ^y - yank kill ring● ^p - previous line● ^n - Next line● <tab> completion for files

Command line editing

● ^f - foward char , ESC-f (word)● ^b - back char , ESC-b (word)● ^s - search forward, ^r search backward● .....

Command line editing

● /tmp● /dev/null● / or /root● /home● /usr (/usr/local, /usr/bin, /usr/lib)● /var (/var/log,/var/lib, /var/tmp, /var/run,

/var/crash,/var/mail,/var/spool,/var/local)● /opt

Common directories

● some shell built-ins, many std, and many add-ons

● Directory navigation / Files○ cd, pwd○ pushd, popd○ ls○ file○ strings○ which○ whereis

UNIX tools............

● find ● locate● touch ● mkfile● sum● nl, wc● cat, zcat, od, hd, echo● grep, egrep● more, less, pg● head● tail

File & display commands

● man, man -k● clear● stty● script● tee● xargs● bc● banner● fortune● spell

Various

● sed, ed● awk● cut● sort● uniq● tr

Manipulate text strings +

● w● who● finger● uptime● uname● hostname● last● top● date , cal

Host related

● time● watch● sleep● kill, pkill, killall● nohup● nice, renice● ps● cron, at

Command Control

● lsof● gdb● strace, ptrace, truss● fuser● ldd● nm

Debugging , monitoring

● sar● iostat● vmstat● mpstat● ipcs,ipcrm● nfsstat●

stats performance

● ifconfig● netstat● route● tcpdump,snoop● nettop● nslookup, dig, ● ping, traceroute● iptables, ipchains

Network

● df● du● mount● exportfs● fdisk● dd● mkfs● tar, dump

disk

● su● chmod● chown● chgrp● groups● passwd● login● acl

Permissions and account