rouben@math9.math.umbc.edu (10/01/90)
The following short script produces incorrect results under ultrix 4.0:
--------- Begin Script -----------------------
#!/bin/sh5
dummy () {
echo This message from dummy
}
set Hello World
echo $1 # These lines
echo $2 # will echo "Hello World"
dummy
echo $1 # These lines
echo $2 # will echo blanks!! They shouldn't.
---------- End Script ---------------------
Notes:
/bin/sh5 is ultrix's counterpart of /bin/sh in System V. Probably its
most significant advantage from a programmer's point of view is its
function defining capability. In the script above the function "dummy" is
defined to echo a string. An unintended side-effect of the execution of
the function dummy is that it clears the shell variable $1 and $2.
This shell script executes correctly on Stardent 3000 which is a hybrid
BSD/SysV machine.
--
Rouben Rostamian Telephone: (301) 455-2458
Department of Mathematics and Statistics e-mail:
University of Maryland Baltimore County rostamian@umbc.bitnet
Baltimore, MD 21228, U.S.A. rostamian@umbc3.umbc.edugwyn@smoke.BRL.MIL (Doug Gwyn) (10/01/90)
In article <4052@umbc3.UMBC.EDU> rouben@math9.math.umbc.edu () writes: >An unintended side-effect of the execution of the function dummy is that >it clears the shell variable $1 and $2. Early versions of the Bourne shell with support for shell functions, for example UNIX System V Release 2, also do this. I don't know whether or not this has been officially "fixed" in later versions of the Bourne shell. Some Bourne-compatible shells do seem to have it fixed.
chet@cwns1.CWRU.EDU (Chet Ramey) (10/01/90)
In article <4052@umbc3.UMBC.EDU> rouben@math9.math.umbc.edu () writes: >The following short script produces incorrect results under ultrix 4.0: It will produce incorrect results for any system whose Bourne shell is derived from the one shipped with System V release 2. This includes at least the HP-UX /bin/sh, Ultrix /bin/sh5, and the SunOS 3.x /bin/sh. These shells keep only a single global list in which to store the positional parameters, and function invocations overwrite this global list. The System V.3 /bin/sh has this fixed. (So does bash, for that matter. :-) Chet -- Chet Ramey ``Levi Stubbs' tears run down Network Services Group his face...'' Case Western Reserve University chet@ins.CWRU.Edu
guy@auspex.auspex.com (Guy Harris) (10/02/90)
>Early versions of the Bourne shell with support for shell functions, for >example UNIX System V Release 2, also do this. I don't know whether or >not this has been officially "fixed" in later versions of the Bourne >shell. The SunOS 4.0.3 Bourne shell does it right, and I don't remember fixing it, so I assume the fix was picked up from the S5R3 or S5R3.1 Bourne shell.