.sp 0.4i
.ft B
.tl 'CSCI-E28'Lecture 3'Outline'
\l'6.5i'

.nf
.in +1i
.ta 1i +1.5i
\fBTopics\fR:	Directories, File Attributes, Bits, File Operations

\fBApproach\fR:	Write our own versions of Unix programs

\fBFeatured Commands\fR:
	ls, ls -l

\fBMain Ideas\fR:
	A directory is a list of file names
	File attributes can be numerical values
	File attributes can be yes/no settings
	Bitwise operations ( |, & )

\fBAgenda\fR
	stdio	fopen/getc/putc/fclose vs open/read/write/close
.sp 6p
	ls1	opendir(), readdir(), closedir()
		not sorted, and does not support -l
.sp 6p
	file attributes	owner, dates, size, type, permissions
		look at chmod(), chown(), chgrp(), touch
.sp 6p
	stat1	stat() system call
.sp 6p
	stat2	coding yes-no attributes as bits
		binary, octal, bit operations
.sp 6p
	ls2	combine ls1 and stat2
		still not sorted, and what about ls -l filename

\fBSections\fR
	0. First, one more item about buffering:
	    * people asked after class about using open,read,write,close
	      vs fopen, getc, putc, fclose -- what's the difference?
	    * Answer - the standard library adds buffering
	      a FILE points to a struct containing a (a) ptr to a buffer,
	      (b) some pointers to keep track of where we are, (c) file
	      descriptor, (d) type of open(read/write/both)
.sp 4p
	      Thus, getc or fgets do what our utmplib do.
	      The include file <libio.h> line 271 has the def
		 
	 1. files have content AND properties
	 2. Using ls
	 3. A brief review of the Unix directory tree
	 4. Is this just like who? open, read, show, close
	 5. What is a directory?
	 6. Reading a directory 
	 7. How close are we to a complete version of ls?
	 8. How do we add the -l option?
	 9. How does stat() work?
	10. What info do we need from what stat tells us?
	11. How do we decode the type and file permissions?
	12. How do we convert uid to logname?
	13. How do we convert gid to group?
	14. Building stat2.c : format info just like ls -l
	15. Can we combine stat2.c with ls1.c ?