Skip to content

Latest commit

 

History

History
58 lines (46 loc) · 3.08 KB

DESIGN.md

File metadata and controls

58 lines (46 loc) · 3.08 KB
Raw

QInstall design documentation

qinstall performs all of its actions by acting on a live directory structure, so the layout is critical for it's operation. Everything is dynamically read from the file system and there is no separate cache. This makes it easy to start using the qinstall system on a new machine or platform.

The QROOT variable is critical to qinstall's operation. Assuming you do not specify a QROOT variable in the environment provided to qinstall, the tool will search for a qinstall root in the following locations in sequence:

  • /qinstall (The most common place to mount the qinstall root)
  • The directory where the qinstall utility was executed from (This was not chosen as a default in case you choose you symlink or copy the qinstall tool into an alternate directory in your path, such as /usr/local/bin)

qinstall then checks if any of the generic parameters were specified on the command line and processes them:

  • -d directory Sets the QINSTALLDIR parameter to the specified directory. This causes qinstall to search for the image to install from the specified directory
  • -p Sets the QPREREQS variable to '1' which triggers the installation of all prerequisite products where possible.
  • -R responsefile Sets the QRESPFILE variable which is frequently used by the .qinstall scripts to override the default response files for the product install

The QPLAT variable is then set to the correct value for the platform we are running on. This is usually from the uname variable, but there are some special cases for AIX and HP-UX. The product and version parameters are set into the QPRODUCT and QVERSION variables.

If a product name, or version name is missing, qinstall will then display the list of available options to the user

qinstall sets QLOCATION to the directory which contains the .qinstall scripts, and QINSTALLDIR is set to the same location if it hasn't already been set (either in the environment or via the -d parameter described earlier)

If the prereqs option has been set, then qinstall finds any suitable .qprereqs file, and recursively calls qinstall for each prerequisite product listed in the file, specifying the -p option so that prerequisites are installed recursively.

The .qinstall script can be located in a number of different locations, so a for loop is executed which checks each of the possible locations (from highest priority to lowest). Once a script is found, the following takes place, and once a script has been executed, the loop is broken (the EXECUTED variable is used to check for this condition):

  • The location of the selected .qinstall script is displayed for debugging
  • The .qinstall script is scanned for the LOGFILES= definition, and the LOGS variable is set to the list of logs defined.
  • The .qinstall script is executed and the output logged

Once this is done, an entry is written to either /var/log/qinstall.log or /var/adm/qinstall.log to indicate what has been done assuming this can be written to (since softweare installations are commonly done with root privileges this shouldn't be a problem