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Week 8 Notes for NET2003
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-Ian! D. Allen - idallen@idallen.ca

Remember - knowing how to find out an answer is more important than
memorizing the answer.  Learn to fish!  RTFM!  (Read The Fine Manual)

Keep up on your readings (Course Outline: average 5 hours/week homework)

Shell syntax:
 - define environment variables and call command, e.g.
   $ LC_COLLATE=en sort /usr/dict/words
   $ LC_COLLATE=C  sort /usr/dict/words
 - variables set on the same command line as a command, before the
   command name, are set only in the environment of the command;
   they are not set locally
 - a quick way to pass in an environment variable without using "export"

  local variable x is not passed to environment (unless exported):
    $ x=foo
    $ echo var is $x
    var is foo
    $ bash
    bash$ echo var is $x
    var is 
    bash$ exit
    $ echo var is $x
    var is foo

  environment variable y is set for one command (not set locally):
    $ echo var is $y
    var is
    $ y=foo bash
    bash$ echo var is $y
    var is foo
    bash$ exit
    $ echo var is $y
    var is

shell "for" loop: for x in a b c d ; do echo $x ; done
 - can use any shell technique to generate the list a b c d
   - e.g. glob pattern:  see /etc/init.d/httpd

special forms of shell script redirection apply to rest of script
  exec 2>&1
  exec <file

Symbolic Links
  - similar to Windows/Mac aliases, but they work even for directories
  - can symlink to directories (cannot hard link to directories)

command-line FTP - File Transfer Protocol
 - See Notes file: file_transfer.txt
 - be careful of binary/text !
 - also available under Windows in a console (DOS) window

Makefile
  - make clean
  - make all
  - make uses meta-character $ for make variables; double it to protect
    it and pass it to the shell, e.g. use: echo $$PATH

Sample Makefile:
  all:
      echo this is the all target
      date
  users:
      echo this is the foo target
      echo "Number of users is: $$( who | wc -l )"
 
  NOTE: words on the same line after the target are dependencies:

  all: foo bar

  - the above means "item 'all' depends on items 'foo' and 'bar'"
  - the Makefile will try to make 'foo' and 'bar' first before making 'all'

Review System V start up scripts and tools
 - helper programs:
   - chkconfig  (any terminal window) [not on Knoppix]
   - ntsysv     (any terminal window) [not on Knoppix]
   - ksysv      (X11 graphical only)

System logging - figuring out where things go wrong
 - logging needs a system log daemon and kernel log daemon running:
 - daemon is started via: /etc/init.d/syslog or /etc/init.d/sysklogd
 - syslog config file: /etc/syslog.conf
   - the config file assigns types of logging to various file names
 - syslog log file directory: /var/log/*