shell arithmetic not POSIX compliant
schweikh at schweikhardt.net
Mon Jun 2 13:14:32 PDT 2003
while trying to configure the POSIX validation suite from the OpenGroup
(VSC-lite) I ran into the following problem. During test script generation
the following syntax appears in a shell script:
: $((tet_l31_testnum += $#))
where tet_l31_testnum is the name of a variable with an integer value
and $# is 1. Our /bin/sh complains about
/home/vsctest1/tet_root/lib/posix_sh/tcm.sh: arith: syntax error: "tet_l31_testnum += 1"
This begs the question is our shell's arithmetic substandard or is the
bug in the script? I'm inclined to say it is a bug in our /bin/sh,
reading the POSIX 2001 sh spec, which refers to the C operators table
and makes these exceptions
<quote IEEE Std 1003.1, 2003 Edition>
The arithmetic expression shall be processed according to the rules given in Arithmetic Precision and Operations , with the following exceptions:
* Only signed long integer arithmetic is required.
* Only the decimal-constant, octal-constant, and
hexadecimal-constant constants specified in the ISO C standard,
Section 126.96.36.199 are required to be recognized as constants.
* The sizeof() operator and the prefix and postfix "++" and "--"
operators are not required.
* Selection, iteration, and jump statements are not supported.
</quote IEEE Std 1003.1, 2003 Edition>
So it appears all assignment ops like += must be supported.
Jens Schweikhardt http://www.schweikhardt.net/
SIGSIG -- signature too long (core dumped)
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