Script portability: Difference between revisions
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x=`expr $x + 1` | x=`expr $x + 1` | ||
</source> | </source> | ||
== 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. | |||
== References == | == References == | ||
* [http://www.novell.com/coolsolutions/feature/11232.html Making Scripts Portable]] by Simon Nattrass | * [http://www.novell.com/coolsolutions/feature/11232.html Making Scripts Portable]] by Simon Nattrass |
Revision as of 12:26, 4 May 2012
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.
- _Simon__Nattrass_
Guidelines
Conditionals
Conditional with [ ... ] should replaced by __test__
if [ -f foo.c ]
then
...
fi
as here:
if test -f foo.c
then
...
fi
Arithmetics
Expression with $(( ... ))
x=$(($x+1))
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.
References
- Making Scripts Portable] by Simon Nattrass