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Using arrays in bash using strings to bash built-in true

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Top Forums Shell Programming and Scripting Using arrays in bash using strings to bash built-in true
# 8  
Old 03-28-2012
Quote:
Originally Posted by kristinu
How about ksh? Can I use associative arrays without worry about using them?
How about trying what I suggested? Did it work, or did it not?

Quote:
Can one do the following in bash?
Code:
false=0
true=1

BASH is not C. I don't see any point in doing this. It's not going to make your code simpler. All you're going to do is make your code more and more complicated and strange.

Learn a tiny bit more about shell programming instead. Use variables as they're intended to be used. It looks unfamiliar to you because it's not familiar. Once you recognize it, it won't be.

What I would do is use bash's -z flag to tell if variables are empty. That way, you don't have to set a thousand different empty variables to zero -- just leave them blank. If they're still blank after processing options, then nobody set them.

Code:
case "$1" in
--something)
        SOMETHING=1
        ;;
esac

if [ ! -z "$SOMETHING" ]
then
        echo "Someone passed the --something option"
fi

This User Gave Thanks to Corona688 For This Post:
kristinu
# 9  
Old 03-28-2012
You could also try Perl, which has associative arrays too, but I think that's just going to make it even more complicated.
# 10  
Old 03-28-2012
Quote:
Originally Posted by Corona688
How about trying what I suggested? Did it work, or did it not?

BASH is not C. I don't see any point in doing this. It's not going to make your code simpler. All you're going to do is make your code more and more complicated and strange.

Learn a tiny bit more about shell programming instead. Use variables as they're intended to be used. It looks unfamiliar to you because it's not familiar. Once you recognize it, it won't be.

What I would do is use bash's -z flag to tell if variables are empty. That way, you don't have to set a thousand different empty variables to zero -- just leave them blank. If they're still blank after processing options, then nobody set them.

Code:
case "$1" in
--something)
        SOMETHING=1
        ;;
esac

if [ ! -z "$SOMETHING" ]
then
        echo "Someone passed the --something option"
fi

I fully agree with you. I had ended up in the situation you describe, with the code getting too complicated. I was looking at removing the setting of lots of variables to zero.

Getting my code on this forum was a way to get input on the way forward. So thanks a lot for your contribution.

---------- Post updated at 12:38 PM ---------- Previous update was at 12:35 PM ----------

Quote:
Originally Posted by Corona688
You could also try Perl, which has associative arrays too, but I think that's just going to make it even more complicated.
Yes, I tried perl and got things more complicated. So abandoned the perl strategy.
# 11  
Old 03-28-2012
I think functions may be helpful to you in simplifying your code, and making it look better to you. In BASH and some KSH you can do this:

Code:
function isset # varname
{
        [ -z "${!1}" ]
}

function notset # varname
{
        [ ! -z "${!1}" ]
}

if isset VARIABLE # Note the lack of $
then
        echo "VARIABLE is set, its value is $VARIABLE"
fi

if notset VARIABLE
then
        echo "VARIABLE is not set"
fi

Last edited by Corona688; 03-28-2012 at 02:53 PM.. Reason: fixing small error
This User Gave Thanks to Corona688 For This Post:
kristinu
# 12  
Old 03-28-2012
Here is an illustration. Unsure if I need to have
Quote:
hasArgument
anymore.

Code:
OLDIFS="$IFS"
IFS="|="                # IFS controls splitting. Split on "|" and "=", not whitespace.
set -- $*               # Set the positional parameters to the command line arguments.
IFS="$OLDIFS"

declare -A hasArgument

while [ "$#" -gt 0 ]
do

  case "$1" in

  "--"[cC][mM][oO][dD]|\
  "--"[cC][mM][oO][dD]"-"[iI][fF][lL])
    shift
    value_cmodIfl="$1"
    hasArgument_cmodIfl=1
  ;;

  "--"[sS][rR][cC][sS]|\
  "--"[sS][rR][cC][sS]"-"[iI][fF][lL])
    shift
    value_srcsIfl="$1"
    hasArgument_srcsIfl=1
  ;;

  "--"[rR][cC][vV][sS]|\
  "--"[rR][cC][vV][sS]"-"[iI][fF][lL])
    shift
    value_rcvsIfl="$1"
    hasArgument_rcvsIfl=1
  ;;

  *)
    value_bdFileLst="$value_bdFileLst $1"
    hasArgument_bdFileLst=1
    hasArgument_bd=1
  ;;

  esac

  shift                 # Skip ahead to the next argument

done

if [ ! -z "$value_cmodIfl" ]
then
   cmodIfl="$value_cmodIfl"
else
   cmodIfl="$dflt_cmodIfl"
fi

# 13  
Old 03-28-2012
I don't think you need any of them at all. You can tell if the variables are blank, why waste more variables storing things you can tell without them?

Also -- just set your defaults in the first place, and let the script change them later if they're given.

Code:
OLDIFS="$IFS"
IFS="|="                # IFS controls splitting. Split on "|" and "=", not whitespace.
set -- $*               # Set the positional parameters to the command line arguments.
IFS="$OLDIFS"

# Just set the default in the first place.
value_cmodIfl="$dflt_cmodIfl"

while [ "$#" -gt 0 ]
do
  case "$1" in

  "--"[cC][mM][oO][dD]|\
  "--"[cC][mM][oO][dD]"-"[iI][fF][lL])
    shift
    value_cmodIfl="$1"
  ;;

  "--"[sS][rR][cC][sS]|\
  "--"[sS][rR][cC][sS]"-"[iI][fF][lL])
    shift
    value_srcsIfl="$1"
  ;;

  "--"[rR][cC][vV][sS]|\
  "--"[rR][cC][vV][sS]"-"[iI][fF][lL])
    shift
    value_rcvsIfl="$1"
  ;;

  *)
    value_bdFileLst="$value_bdFileLst $1"
  ;;

  esac

  shift                 # Skip ahead to the next argument

done

if [ ! -z "$value_rcvsIfl" ]
then
        echo "rcvsIfl given"
fi

# 14  
Old 03-28-2012
I am getting a bit of problems with the following.

Output shows

Code:
agr1 set to 
agr2 set to file.cmod

Code:
#!/bin/bash

function isSet
{
    [ ! -z "$1" ]
}

function notSet
{
    [ -z "$1" ]
}

agr2="file.cmod"

if isSet agr1; then
  echo "agr1 set to $agr1"
fi

if notSet agr1; then
  echo "agr1 not set"
fi

if isSet agr2; then
  echo "agr2 set to $agr2"
fi

if notSet agr2; then
  echo "agr2 not set"
fi
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