Working with the Unix OS

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Processes II } pause(); /* wait for a signal */ void sigintHandler() { printf("process %d got a SIGINT\n", getpid()); } parent PID 583 PGRP 583 waits child PID 584 PGRP 583 waits ^C process 584 got a SIGINT process 583 got a SIGINT /* proc_group2.c */ #include #include void sigintHandler(); main() { int i; signal (SIGINT, sigintHandler); /* handle ^C */ } if (fork() == 0) setpgrp(0, getpid()); /* place child in own process group */ printf("process PID %d PGRP %d waits\n", getpid(), getpgrp(0)); sleep(5); /* time to ^C */ for (i=0; i
Processes II } /* child */ signal (SIGTTIN, sigintHandler); setpgrp(0, getpid()); /* place child in new process group */ printf("enter a string: "); scanf ( "%s", str); /* try to read from control terminal */ printf("you entered %s\n", str); } else wait(&status); /* wait for child to terminate */ void sigintHandler() { printf("attempted inappropriate read from control terminal\n"); exit(1) ; } enter a string: attempted inappropriate read from control terminal PIPES Interprocess communication mechanism that allow two or more processes to send information to each other. Used to connect standard output of one utility to standard input of another. $ who | wc -1 Both the writer process and the reader process of a pipeline execute concurrently, a pipe automatically buffers the output of the writer and suspends the writer if the pipe gets too full. UNNAMED PIPES pipe(fd) - unidirectional communication link fd[0]---------------------------------------------------- write end | . |--->pipe--->| . | read end fd[l]----------------------------------- For bidirectional communication use two pipes /* talk.c */ #include #define READ 0 #define WRITE 1 char* phrase = "a line of text for talk"; main() { int fd[2], nread; char str[100]; } pipe(fd); /* create unnamed pipe */ if(fork()== 0){ /* child writer */ close(fd[READ]); /* close unused end */ write(fd[WRITE], phrase, strlen(phrase)+1); close(fd[WRITE]); /* close used end */ } else {/* parent reader */ close(fd[WRITE]); /* close unused end */ nread = read(fd[READ], str, 100); printf("read %d bytes: %s\n", nread, str); close(fd[READ]); /* close used end */ } 128
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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()){
Page 79 and 80: C Libraries What is curses? - libra
Page 81 and 82: C Libraries } if ((fd=fopen(argv[1]
Page 83 and 84: Introduction to kernel 7. INTRODUCT
Page 85 and 86: 82 Introduction to kernel Programs
Page 87 and 88: Introduction to kernel } { printf("
Page 89 and 90: Introduction to kernel The kernel r
Page 91 and 92: Introduction to kernel UNIX Interna
Page 93 and 94: Introduction to kernel File System
Page 95 and 96: Introduction to kernel Every proces
Page 97 and 98: Processes I Process States 1. Execu
Page 99 and 100: Processes I } printf("%d %s\n", cnt
Page 101 and 102: Processes I dup (and other similar
Page 103 and 104: Processes I The u area contains - p
Page 105 and 106: Processes I The Context of a Proces
Page 107 and 108: Processes I Process Control use and
Page 109 and 110: Processes I Although the processes
Page 111 and 112: Processes I Handling Signals - proc
Page 113 and 114: Processes I USER=neville PATH=/user
Page 115 and 116: Processes I ! Shadow Password /etc/
Page 117 and 118: struct timeval { long tv_sec; /* se
Page 119 and 120: Processes I F_SETFL set status flag
Page 121 and 122: Processes I process is the child pr
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: Processes II } while (1){ printf("p
Page 133 and 134: Processes II int readline(int fd, c
Page 135 and 136: Processes II { } char process_name[
Page 137 and 138: Processes II - Pipe in a single pro
Page 139 and 140: Processes II System V IPC - message
Page 141 and 142: Processes II int msgctl(int msqid,
Page 143 and 144: Processes II For every semop operat
Page 145 and 146: Processes II /* client loop */ mesg
Page 147 and 148: I/O Subsystem Drivers frequently sl
Page 149 and 150: I/O Subsystem Terminal Drivers - In
Page 151 and 152: I/O Subsystem Canonical Mode algori
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
Page 163 and 164: Interprocess Communication for (i=0
Page 165 and 166: Interprocess Communication /* struc
Page 167 and 168: Interprocess Communication ! Compar
Page 169 and 170: … connect(sockfd,(struct sockaddr
Page 171 and 172: Interprocess Communication Address
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
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Process Scheduling Figure 57. Mappi
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Figure 62. Sequence of Swapping Ope
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Buffer Cache The kernel takes buffe
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Buffer Cache The kernel places the
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Buffer Cache Process B will find th
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Unix Administration 14. UNIX ADMINI
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Unix Administration Example output
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Unix Administration *) IN=-mtime -2
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Unix Administration Load /Unix kern
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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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