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run: expect from bash vs. shell-utils from expect

Posted by doublea1535 (doublea1535), 22 August 2006
I am curious about some of the long-term or more in-depth challenges associated with :

1) Running "exec command" commands from within expect. Reasons for this are string manipulation(sed,awk), file manipulation, calling external scripts.


2) Calling expect from within a bash shell. Reasons to do this are : easy option/argument handling via getopts, more comfortable scripting environment; bash regexps/globbing.

Does calling expect from within bash add a serious amount of complexity? Tcl is powerful but I don't need anything that it provides really; at least so far bash and UNIX shell coreutilities seem to be able to do everything I need, and I am much more familiar with them. Is bash able to (quantitatively) process external commands more efficiently than Tcl?

Sorry for the long question. I am really just looking for someone to point me in the right direction of some high-level programming concepts (that I could look further into myself) or a quick blurb.

Thanks much!  

Posted by admin (Graham Ellis), 23 August 2006
Shell programming and core utilities are very powerful indeed for simpler operating system scripting operations, but they become progressively harder to use, and progressively less efficient, as the size of your code / application grows, or when you need portability across operating systems.  

There's no hard and fast rule as to when you should say that a job is too much for shell programming and move across to (say) Tcl, Python or Perl - in other words, there's a big grey area between jobs that are easily done with any of these languages or with shell, and jobs for which it's worth going to all the trouble of learning a new language to support.  Only you can be the best judge os where the crossover point is for you personally.

Posted by doublea1535 (doublea1535), 23 August 2006
Thank you much for the feedback Graham.

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