Hallo Ralf! > It seems that it is impossible to replace a forward slash in a > variable expansion, even if the slash is quoted: The version of ash in busybox has a long standing bug in the quote handling code ... and I'm the one whoe probably produced this bug!
Years ago, as far as I remember it was somewhat at the beginning of the 90s, I dig deep into the code of ash and bash to create a modified shell version for a special purpose. The final version of this hell was based on the original version of ash, with several modifications and major hacks from me. After creating that special shell, I wanted to have a normal unix shell, which is small and compatible in it's normal behavior to that special shell. Due to the fact, I lost the original code of ash, I stripped of the extensions, which made the other shell special. And used that version under the name ash. Neither the special shell, nor the stripped down version I used as ash, were officially distributed and I never mentioned my modifications or my name in the source code ... but exactly this stripped down version of ash made it into busybox ... I don´t know how the hell it did! The major difference between the original ash version and my modified version were a couple of code size improvements and source code clearance work I did. Those changes are really welcome to the philosophy of busybox, I think, and there is nothing wrong with it, that they got used within busybox ... but beside those welcome changes, I introduced two major bugs in my ash version ... and both have been included in busybox too ... One bug was in code that tried to deal with this pipe/loop/subshell problem ... it tried to catch that situation and run the loop in the current shell, but was buggy and it seems to be that code part has been removed from busybox in an early version (I think ist was anywhere in the 0.50er or 0.60er line). The code substituted looks more like the code from the original ash. And the second bug, which I couldn't track down until now, is that one in the shell quote handling. I mangeld with this, without really understanding, how it worked (blame me). My code changes removed a problem (not bug) that a had in the specialized shell version but introduced some spurious behavior when quotes get mixed up or nested. The only thing I can tell is, the code in busybox works, if you reduce the level of quoting. That is, don't do too much at once. Do it in several steps, assigning the result of string mangling to variables and use those variables as simple substitutions in further steps. This is the story of busybox ash and the reason why there are major differences between the original ash manpage and the ash version in busybox. I introduced those differences (and bugs) without noting them anywhere but I never expected those coming up in any other officially distributed version :-( -- Harald _______________________________________________ busybox mailing list [email protected] http://lists.busybox.net/mailman/listinfo/busybox
