As usual with 4os2, it's not a bug it's a feature. From the 4os2 help file:
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You can also use the square bracket wildcard syntax to work around a conflict between long filenames containing semicolons [;], and the use of a semicolon to indicate an include list. For example, if you have a file on an HPFS drive named C:\DATA\LETTER1;V2 and you enter this command:
[c:\] del \data\letter1;v2
you will not get the results you expect. Instead of deleting the named file, 4OS2 will attempt to delete LETTER1 and then V2, because the semicolon indicates an include list. However if you use square brackets around the semicolon it will be interpreted as a filename character, and not as an include list separator. For example, this command would delete the file named above:
[c:\] del \data\letter1[;]v2
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Or, as mentioned, you could just use CMD.EXE
This is why it is best to have CMD.EXE as the default command processor in your CONFIG.SYS and then add a button to eCenter for 4os2. Install programs and such will then work in an environment they expect and YOU get to use all those nice extras in 4os2.