Working with the Unix OS

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I/O Subsystem 10. I/O SUBSYSTEM - device driver - disk and terminal - software devices e.g. memory - implementation via - streams DEVICE INTERFACES - block device - character "raw" device Device configuration data - hard code into files that are compiled into kernel, or - supply configuration information while system running, or - self-identifying devices permit kernel to recognize what is installed. Figure 27. Driver Entry Points mknod /dev/device_name c/b_special major_no minor_no block device switch table entry open close strategy 0 gdopen gdclose gdstrategy 1 gtopen gtclose gtstrategy character device switch table entry open close read write ioctl 0 conopen conclose conread conwrite conioctl 1 dzbopen dzbclose dzbread dzbwrite dzbioctl 2 syopen nulldev syread sywrite syioctl 3 nulldev nulldev mmread mmwrite nodey 4 gdopen gdclose gdread gdwrite nodev Figure 28. Block and Character Device Switch Tables 143
I/O Subsystem Drivers frequently sleep, waiting for hardware connections or the arrival of data. algorithm open /* for device drivers */ input: pathname openmode output: file descriptor { convert pathname to inode, increment inode reference count, allocate entry in file table, user file descriptor, as in open of regular file; get major, minor number from inode; save context (algorithm setjmp) in case of long jump from driver; if (block device) { use major number as index to block device switch table; call driver open procedure for index: pass minor number, open modes; } else { } use major number as index to character device switch table; call driver open procedure for index: pass minor number, open modes; } if (open fails in driver) decrement file table, inode counts; Figure 29. Opening a Device Open with "no delay", call returns immediately Figure 30. Closing a Device algorithm close /* for devices */ input: file descriptor output: none { do regular close algorithm; if (file table reference count not 0) goto finish; if (there is another open file and its major, minor numbers are same as device being closed) goto finish; /* not last close after all * / if (character device) { use major number to index into character device switch table; call driver close routine: parameter minor number; } if (block device) { if (device mounted) goto finish; write device blocks in buffer cache to device; use major number to index into block device switch table; call driver close routine: parameter minor number; invalidate device blocks still in buffer cache; } finish: release inode; } 144
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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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Page 99 and 100: Processes I } printf("%d %s\n", cnt
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Page 103 and 104: Processes I The u area contains - p
Page 105 and 106: Processes I The Context of a Proces
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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
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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: Processes II /* client loop */ mesg
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Page 153 and 154: I/O Subsystem Raw Mode Raw mode is
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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 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
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
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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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