A bash Tool

I was writing a bash script the other day, and got fed up with having to take seperate steps to handle a lot of the routine steps to make it useable. So, I piled them all together. This bundles together several ideas I been exposed to in the last week.

---

#!/usr/bin/env  bash

#     -  See 'man env' and the discussion involving 'env'
#        and invoking Perl
#        in "Programming Perl", by Larry Wall

#   bcmp, Bash "CoMPiler"
#   this program really just runs some housekeeping
#   chores you should do before trying to run a bash script.
#   This is partly inspired by a discussion of software
#   configuration management I read somewhere
#   (source forgotten) discussing the nightly 'build'
#   of some perl scripts, which rather than compiling them
#   they were put through regressions tests to verify they
#   were ready to run.
#   Many of the commands used in this were things I'd come
#   across lately that seemed to fit in with this idea.
#
#   7 June 2008 Dallas E. Legan II

USAGE="${0##*/}   -h | <script>"  ;

THESCRIPT=${1:?"What script file? Usage: ${USAGE}"}  ;

[ -f ${THESCRIPT} ]  || { echo ${USAGE}  ; exit ; }   ;

set -e    ;

#     - This causes bash to go into 'abort on command error' mode
#       See "Linux Journal", Feb. 2008, p. 10, "Letters"
#       "mkdir Errors Even More Trivial", Ed L. Cashin
#       http://www.linuxjournal.com/article/9957
#       This is also documented in 'man bash' and 'help set'
#       in somewhat obscure, too understated a way.
#       9 July 2008 addition:
#       This is also referenced in
#       the "bash Cookbook",
#       Carl Albing, JP Vossen & Cameron Newham
#       O'Reilly, (C) 2007
#       ISBN-10: 0-596-52678-4
#       ISBN-13: 978-0-596-52678-8
#       http://www.bashcookbook.com/
#       p. 75 - 76
#       Recipe 4.6 "Using Fewer if Statements"

sed  -i 's/ *$//'   ${THESCRIPT}  ;

#      - to strip out trailing blanks, particularly annoying
#        after '\'   'line continuations'
#        '-i' causes 'editing in place'.
#        (Addition 1 July 2008:)
#        I came across another reason for this
#        in the "bash Cookbook",
#        p. 57 - 59,
#        Recipe 3.3 "Preventing Weird Behaviour in a Here-Document"
#        'trap' on page 59 in particular.
#        Basicly, trailing spaces on here document delimiters
#        can cause a bad day.
#        --
#        Alternatively, this might be done using
#        'ed', to make it more traditional and portable.


#       For now, I'm leaving out this idea,
#       but you might want to install some commands
#       to verify that the number of
#       '('  == ')'   (outside 'case' statements)
#       '['  == ']'
#       '{'  == '}'
#       Total number of "'" and '"' are even, etc.
#       Seperate checks for these might make
#       make interpreting the results easier to figure out.

chmod  ugo+x   ${THESCRIPT}   ;

#     - simply to set the permissions to executable

bash -n  ${THESCRIPT}  ;

#     - to do a simple syntax check
#       per the "bash Cookbook",
#       p. 476 - 477
#       Recipe 19.12 "Testing bash Script Syntax"
#       also 'man bash' and 'help set',
#       where this is obscurely documented.

cp ${THESCRIPT}   ~/bin/   ;

#     - Lastly, copy the script to a directory in PATH,
#       this could be any satisfactory location.

#       You might also want to check the script into some
#       version control system at this point,
#       or runs some functional/regression tests.

echo  ${THESCRIPT}   seems ready to run    ;
#  9 July 2008 addition:
#  This is an idea Garth told me about while at
#  Rockwell - when it doesn't conflict with the
#  purpose of the program, it's good to have a
#  message telling if it succeeded or not.
#  This was in the mainframe world,
#  and this can conflict with the needs of
#  Unix programs, but a good idea when practical.
#        END OF SCRIPT