Make GRASS shell scripts portable
- Portable shell scripting is something of a black art, since with the evolution and derivation of the UNIX shell, the definition of "portable" is perhaps ambiguous.
Conditional with [ ... ] should replaced by __test__
if [ -f foo.c ] then ... fi
if test -f foo.c then ... fi
Expression with $(( ... ))
are more portable if using __expr__
x=`expr $x + 1`
The $(command) expression versus `command`
The $(command) may be supported in many modern Bourne shells but for pure Bourne shells use of `command` is favored, although this method tends to lead to confusion when the backquotes contain the characters $, ` and \. In such cases remember to use the character \ to escape these sequences.
- Making Scripts Portable] by Simon Nattrass