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PDL for base VNS config script: setup.sh
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- Ian! D. Allen - idallen@idallen.ca - www.idallen.com

This PDL for the base VNS setup.sh is cumulative up through Lab 8 and Lab 9.
Lab 8 and Lab 9 entries are marked.

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START PDL for base VNS config script: setup.sh

SET up shell environment (#!, PATH, umask, etc.)

SET shell variables for use in rest of script, e.g. hostname, disk

IF ntpd is NOT running
    update Debian packages (optional)
    fetch and install the NTP Internet Time daemon packages
    run the start-up script for the ntpdate package
    run the start-up script for the NTP package
ELSE (optional)
    stop the NTP daemon (using its start-up script)
    run the start-up script for the ntpdate package
    run the start-up script for the NTP package
ENDIF

PRINT the current date

IF virtual disk is NOT mounted
    PRINT warning on stderr
    create mount point under /mnt
    IF mounting the disk on the mount point FAILS
        PRINT an error message on stderr
        EXIT the script with non-zero status
    ENDIF
    PRINT message saying disk was mounted
    RUN df on virtual disk to show that the disk is correctly mounted
ENDIF

Fix the /host symlink to point to the virtual disk (Lab 8)

Enable ip_forward and log_martians; disable rp_filter (Lab 8)
Make sure each of these has the correct value

Enable iptables MASQUERADE on eth0 (Lab 8)

Fix the Daylight Savings problem using a new localtime file (Lab 8)

Clean away unnecessary cache files (Lab 9)

Make sure sshd is running, start it if not (Lab 9)

Make sure we have three hubs started, start hub UI if not (Lab 9)

Stop the machine from halting when the X server exits (Lab 9)
Kill the xsession script

Create a system log directory and fix system logging to use it (Lab 9)
Kill both log daemons (because of bug in start-up script)
Restart both log daemons

Copy our vns DNS resolv.conf (set by DHCP) to the virtual disk (Lab 9)

# We want to move or symlink $HOME .uml and virtuals to the virtual disk.
# This section below has been hugely reworked to prevent/detect common errors.
# You can keep your current (working, we hope) script, or you can
# replace it with this verbose version that will detect errors much better.
#
IF virtual disk/virtuals is a symlink (-L)
    PRINT an error message on stderr
    EXIT the script with non-zero status
ENDIF
IF virtual disk/virtuals exists (-e) and is NOT a directory (! -d)
    PRINT an error message on stderr
    EXIT the script with non-zero status
ENDIF
IF virtual disk/.uml is a symlink (-L)
    PRINT an error message on stderr
    EXIT the script with non-zero status
ENDIF
IF virtual disk/.uml exists (-e) and is NOT a directory (! -d)
    PRINT an error message on stderr
    EXIT the script with non-zero status
ENDIF

# we get here if the virtual disk either has nothing or has real directories

IF virtual disk/virtuals does NOT exist (! -e)
    PRINT message about setting up virtual disk
    IF virtual disk/.uml exists (-e)
        PRINT an error message on stderr (inconsistency found)
        EXIT the script with non-zero status
    ENDIF

    # check the items in the $HOME directory before moving them
    #
    IF $HOME/virtuals is a symlink (-L) or is NOT a directory (! -d)
        PRINT an error message on stderr
        EXIT the script with non-zero status
    ENDIF
    IF $HOME/.uml is a symlink (-L) or is NOT a directory (! -d)
        PRINT an error message on stderr
        EXIT the script with non-zero status
    ENDIF

    MOVE $HOME/virtuals to virtual disk/virtuals
    SYMLINK virtual disk/virtuals into $HOME/virtuals
    MOVE $HOME/.uml to virtual disk/.uml
    SYMLINK virtual disk/.uml into $HOME/.uml

    PRINT long listing of $HOME/.uml and $HOME/virtuals
    EXIT the script with zero status
ENDIF

# we get here only if virtual disk/virtuals is a real directory

IF virtual disk/.uml does NOT exist
    PRINT an error message on stderr (inconsistency found)
    EXIT the script with non-zero status
ENDIF

IF virtual disk/.uml/umlsettings is missing or zero size (! -s)
    PRINT an error message on stderr
    EXIT the script with non-zero status
ENDIF

# check the items in the $HOME directory before deleting them

IF $HOME/virtuals is already a symlink
    IF $HOME/.uml is already a symlink
        PRINT message that symlinks already exist - nothing to do
        PRINT long listing of $HOME/.uml and $HOME/virtuals
        EXIT the script with zero status
    ENDIF
    PRINT an error message on stderr (inconsistency found)
    EXIT the script with non-zero status
ENDIF

IF $HOME/virtuals is NOT a directory or $HOME/.uml is NOT a directory
    PRINT an error message on stderr
    EXIT the script with non-zero status
ENDIF

# make sure nobody is using a UML that we are trying to move

count = count the files under $HOME/.uml
IF count > 1 
    PRINT an error message on stderr (someone is using a UML)
    EXIT the script with non-zero status
ENDIF

count = count the files under $HOME/virtuals
IF count > 0 
    PRINT an error message on stderr (someone is using a UML)
    EXIT the script with non-zero status
ENDIF

# remove the two $HOME directories and link them to the virtual disk

# don't use a recursive remove, in case it has files in it already
# we want this remove to fail if virtuals has files in it (should be empty)
#
PRINT message about removing $HOME/virtuals
IF remove directory $HOME/virtuals FAILS
    PRINT an error message on stderr (someone is using a UML)
    EXIT the script with non-zero status
ENDIF

PRINT message about removing $HOME/.uml
IF recursively remove directory $HOME/.uml FAILS
    PRINT an error message on stderr
    EXIT the script with non-zero status
ENDIF

PRINT message about linking
SYMLINK virtual disk/virtuals into $HOME/virtuals
SYMLINK virtual disk/.uml into $HOME/.uml

PRINT long listing of $HOME/.uml and $HOME/virtuals

EXIT the script with zero status

END PDL for setup.sh