If your application is sensitive to mixed case, move it into the /QOpenSys file system, or into a user-defined file system that has been created as case-sensitive.
The interfaces of operating systems, such as AIX® and Linux®, generally differentiate between uppercase and lowercase letters. On i5/OS™, that is not always the case. You should be aware of several situations in particular where case sensitivity might cause complications with existing code.
Case sensitivity on a directory or file basis depends on the file system you are using on i5/OS. The /QOpenSys file system is case sensitive, and you can create a user-defined file system (UDFS) that is case sensitive.
The following examples are problems stemming from case sensitivity that you might encounter.
In this example, the shell does a character comparison of the generic name prefix against what is returned by readdir(). However, the QSYS.LIB file system returns directory entries in uppercase, so none of the entries matches the lowercase generic name prefix.
$ ls -d /qsys.lib/v4r5m0.lib/qwobj* /qsys.lib/v4r5m0.lib/qwobj* not found $ ls -d /qsys.lib/v4r5m0.lib/QWOBJ* /qsys.lib/v4r5m0.lib/QWOBJ.FILE
This example is similar to the first example except that, in this case, the find utility is doing the comparison, and not the shell.
$ find /qsys.lib/v4r5m0.lib/ -name 'qwobj*' -print $ find /qsys.lib/v4r5m0.lib/ -name 'QWOBJ*' -print /qsys.lib/v4r5m0.lib/QWOBJ.FILE
The ps utility expects user names to be case-sensitive and therefore does not recognize a match between the uppercase name specified for the -u option and lowercase names returned by the i5/OS PASE runtime function getpwuid():
$ ps -uTIMMS -f UID PID PPID C STIME TTY TIME CMD $ ps -utimms -f UID PID PPID C STIME TTY TIME CMD timms 617 570 0 10:54:00 - 0:00 /QOpenSys/usr/bin/-sh -i timms 660 617 0 11:14:56 - 0:00 ps -utimms -f