Working with the Unix OS

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I/O Subsystem 4. Put a character on the end of a Clist (allocates a new CBlock if needed). 5. Remove a group of characters from the beginning of a Clist one CBlock at a time. 6. Can place CBlock of characters onto the end of a Clist Figure 33. Removing characters from a Clist Figure 34. Placing characters on a Clist Terminal Driver Data Structures - Output Clist - 'raw' input Clist - 'cooked' input Clist 147
I/O Subsystem Canonical Mode algorithm terminal write { while (more data to be copied from user space) { if (tty flooded with output data) { start write operation to hardware with data on output clist; sleep (event: tty can accept more data); continue; /* back to while loop */ } copy cblock size of data from user space to output clist: line discipline converts tab characters, etc; } start write operation to hardware with data on output clist; } Figure 35. Writing Data to a Terminal If number of characters on output clist becomes greater than a high-water mark, the line discipline calls driver procedures to transmit the data on the output clist to the terminal and puts the writing process to sleep. When the amount of data on the output clist drops below a low-water mark, the interrupt handler awakens all processes asleep on the event, the terminal can accept more data. When multiple processes write out to a terminal, garbled output results but this is normally permitted. char form[ ] - "this is a sample output string from child "; main() { char output[128]; int i; for (i = 0; i < 18; i++) { switch (fork()) { case -1: /* error --- hit max procs */ exit(); default: /* parent process */ break; case 0: /* child process */ /* format output string in variable output */ sprintf(output, "%s%d\n%s%d\n", form, i, form, i); for (;;) write(1, output, sizeof(output)); } } } Figure 36. Flooding Standard Output with Data - Standard CBlock size is 64 bytes - A Read may request N characters but get M characters 148
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UNIVERSITY OF ATHENS DEPARTMENT OF
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Figure 27. Driver Entry Points.....
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Introduction to Unix ! Execution ma
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Introduction to Unix It works in th
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Introduction to Unix * matches 0 or
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Introduction to Unix vi file-name s
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Introduction to Unix 1,$s/^/>>/ 1,$
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Introduction to Unix ! Special Devi
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Introduction to Unix Working with F
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Introduction to Unix ! Communicatio
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Unix Shells 2. UNIX SHELLS Back Quo
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Unix Shells ! CASE Statement case t
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Unix Shells two lines !Y@Y@Z@Z@ZY c
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Unix Shells if $append then tee -a
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C Programming - Basics main() { int
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C Programming - Basics e.g. i += 2
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External Variables A C program cons
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C Programming - Basics main.c #incl
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C Programming - Basics default: pri
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C Programming - Basics struct tnode
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Unix Tools 4. UNIX TOOLS Tools of t
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Unix Tools Korn shell ! .profile HI
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Unix Tools grep "$name" $PHONEBOOK
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Unix Tools awk '$3 > 0 { print $1,
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Unix Tools END { print max, maxline
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Unix Tools Let an example input fil
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Unix Tools Brown eqn 1 # output Jon
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Development Tools Make looks at the
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Development Tools /* compute size o
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Development Tools #endif #line cons
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Development Tools 1.1 5 lines Retri
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Development Tools In Emacs, you may
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Development Tools */ %{ #define YYS
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C Libraries 6. C LIBRARIES Input an
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C Libraries } while (!feof(fp1)) pu
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C Libraries } free(p); /* what is w
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C Libraries } if ((fp->flag&( _READ
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C Libraries /* dirwalk: apply fcn t
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C Libraries } switch (pid=fork()){
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C Libraries What is curses? - libra
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C Libraries } if ((fd=fopen(argv[1]
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Introduction to kernel 7. INTRODUCT
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82 Introduction to kernel Programs
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Introduction to kernel } { printf("
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Introduction to kernel The kernel r
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Introduction to kernel UNIX Interna
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Introduction to kernel File System
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Introduction to kernel Every proces
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Processes I Process States 1. Execu
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Page 113 and 114: Processes I USER=neville PATH=/user
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Page 119 and 120: Processes I F_SETFL set status flag
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Page 123 and 124: Processes I Rules about sharing of
Page 125 and 126: Processes II 9. PROCESSES (II) FORK
Page 127 and 128: Processes II /* background.c */ #in
Page 129 and 130: Processes II } while (1){ printf("p
Page 131 and 132: Processes II } /* child */ signal (
Page 133 and 134: Processes II int readline(int fd, c
Page 135 and 136: Processes II { } char process_name[
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Page 139 and 140: Processes II System V IPC - message
Page 141 and 142: Processes II int msgctl(int msqid,
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Page 145 and 146: Processes II /* client loop */ mesg
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Page 149: I/O Subsystem Terminal Drivers - In
Page 153 and 154: I/O Subsystem Raw Mode Raw mode is
Page 155 and 156: Figure 43. Pushing a Module onto a
Page 157 and 158: Interprocess Communication } { ptra
Page 159 and 160: Interprocess Communication T ID KEY
Page 161 and 162: Interprocess Communication }; int m
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Page 167 and 168: Interprocess Communication ! Compar
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Page 173 and 174: Process Scheduling Page Tables and
Page 176 and 177: Figure 49. Tie breaker rule Process
Page 178 and 179: Process Scheduling Clock - restart
Page 180 and 181: Process Scheduling Figure 57. Mappi
Page 182 and 183: Figure 62. Sequence of Swapping Ope
Page 184 and 185: Buffer Cache The kernel takes buffe
Page 186 and 187: Buffer Cache The kernel places the
Page 188 and 189: Buffer Cache Process B will find th
Page 190 and 191: Unix Administration 14. UNIX ADMINI
Page 192 and 193: Unix Administration Example output
Page 194 and 195: Unix Administration *) IN=-mtime -2
Page 196 and 197: Unix Administration Load /Unix kern
Page 198 and 199: Unix Administration for (i=0; i&i d
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Unix Administration fi done echo $s
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Unix Administration New Software !
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Unix Security Example: group name:g
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Unix Security $ crypt < exam320.Z >
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Unix Security - exported filesystem
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Unix Security system(cmdstr); $ ech
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Unix Security - repairs damaged use
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Working with the Unix OS

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