Making Unix equate with MPE
October 10, 2006
File equations are a 3000 speciality in an IT operation, "the commands that redefine the attributes of a file, including perhaps the actual filename," according to our friends at Robelle. Since Unix doesn't have file equations, customers who are making their transition need to learn how to make Unix's symbolic links report what a 3000 manager once learned from a LISTEQ command.
Up on the 3000-L newsgroup a customer asked what he might use to do the work of LISTEQ on a Unix system. 3000 managers are used to checking file equations when something mysterious happens with an MPE file.
Dave Oksner of 3000 application vendor Computer And Software Enterprises (CASE) offered the 'find' command as a substitute in Unix/Posix, telling it to only process files of type "symbolic link."
Oksner's example of substituting find for LISTEQ:
find /tmp/ -type l -exec ls -l {} \;
which would start from the /tmp directory, look for symbolic links, and execute “ls -l” on the filenames it finds. You could, of course, eliminate the last part if you only wanted to know what the filenames were and get
find /tmp/ -type l
(I believe it’s the same as using ‘-print’ instead of ‘-exec [command]’)
Beware of output to stderr (if you don’t have permission to read a directory, you’ll get errors) getting interspersed.
HP's Jeff Vance added that the command interpreter in MPE also can deliver file information through a listfile command:
Don't forget the CI where you can do:
:listfile @,2;seleq=[object=symlink]
:help listfile all shows other options.
HP's come up with a MPE-to-Unix command resource online to help with this sort of thing. Our former Inside COBOL columnist and product reviewer Shawn Gordon offers his own MPE vs. Unix paper, and Robelle's experts wrote a column contrasting Unix shell scripts with MPE tools in Robelle Tech in the NewsWire.
HP's also got free training available to help make these comparisons. John Burke reviewed the options in a 2002 column for the NewsWire. These online classes are still free