VMS/IRAF Installation and Site Manager's Guide

8.4. Precompiling TERMCAP and GRAPHCAP entries

Precompilation of a termcap or graphcap entry is a technique used to speed runtime access of the entry for that device. If the entry is not precompiled the termcap or graphcap file must be physically opened and scanned at runtime to read the desired entry. This causes a slight delay when clearing the terminal screen or plotting a graph, hence it may be worthwhile to cache the entries for commonly used video and graphics terminals. We do not recommend that sites attempt to relink the IRAF system to cache new terminal device entries, but system managers may wish to be aware of this option.

The system comes with selected termcap and graphcap entries already precompiled. To see which devices are precompiled, page the cache data files, dev$cachet.dat (for termcap) and dev$cacheg.dat (for graphcap). To cache a different set of entries one must regenerate these files with the mkttydata task in the SOFTOOLS package, and then do a full sysgen relink with the mkpkg utility. Detailed instructions are given in the manual page for mkttydata.^*

^*Important Note: If the system is configured to use the IRAF shared library (the default), you must update the system libraries (§9.7.2) and rebuild the shared library (§9.7.3) before relinking the system (§9.7.4), else the changes to the termcap and graphcap cache files will have no effect. The use of the shared library is peculiar to VMS/IRAF and is not discussed in the mkttydata documentation.