Bourne Again Shell
==================
I had written a little animation in 'bash' - the famous UNIX shell using
the famous ANSI escape sequences. Then published it on SourceForge. It is yet
another animation of Towers of Hanoi
(
https://sourceforge.net/projects/towers-of-hanoi-in-bash/files/). The last
change was hiding the annoying cursor that follows the long spaces forming
the discs.
Maybe, my next step will be to make variables defined in functions local.
You can do it by adding the word "local" before the first assignment to the
variable.
Bash is advanced compared to other shells, such as 'sh', 'ksh', 'csh' and
'tcsh'. You can enjoy some capabilities by doubling the brackets or
parentheses. Brackets are used for tests with conditional expressions, and
double brackets can be used for testing extended conditional expressions. For
example, you can check
if a string matches a regular expression.
In the man page, you can find it under:
SHELL GRAMMAR->Compound Commands->[[ Expression ]]
Double parentheses allows you to write an expression like in a more convenient
way like in C, Perl, AWK, Javascript, etc. For example, you can use it in 'for'
loops. Or you can use the value of a variable without a preceding $. For
example,
((i++))
will add 1 to i returning its old value. The traditional way to increment a
variable
is by using the command:
i=`expr $i + 1`
In the man page, you can find it under:
SHELL GRAMMAR->Compound Command->((expression((
Use the man page for bash if you want to get help offline, and the manual page
you get into by typing
man <command>
is the man page of BUILTINS(1).
Unfortunately, man pages do not contain a TOC with links to sections.
Another resource is the irc channel #
[email protected]
*Connect to irc.freenod.net, and join #bash).
The channel is very active, and you can find there an answer to your question
even without asking it. Somebody else will ask the question for you, and you
can learn the programming language just by viewing the discussion. Maybe the
user 'graycat' will refer you to a relevant site using the bot 'graybot'.
