LinuxQuestions.org - [SOLVED] Problem with getting array from function (bash)

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- - Problem with getting array from function (bash) (https://www.linuxquestions.org/questions/programming-9/problem-with-getting-array-from-function-bash-756635/)

Quote:

Originally Posted by chrism01 (Post 3695030)

You could just put

set -xv

as the 2nd line of your code. It shows everything before and after substitutions etc as it goes.
Great for debugging.
:)

I used to use set -xv (and set +xv to turn it off) all the time but do so much less, now that I use $(<command> 2>&1) on almost all commands to capture their output for error trapping and reporting. With set -xv on, all those commands generate unexpected output!

Now I've reverted to echoing key variable names as required and sometimes to short set -xv blocks.

Using command output capture to tell the user about progress (on screen and log) identifies the part of the script that failed quite closely.

Ah, but with your experience, you usually have a good idea which parts are (probably) going wrong. Initially, for new users or really obscure problems, one set -xv at the top is highly informative. You can always be more specific later.

Absolutely. Actually, day or two before I started this thread I tried "bash -x <scriptname>".

But frankly, I believe that nothing beats good echo command with custom text like:

Code:

echo "Variable K after the change is "$K

My current main script has ~950 lines, but around half of them are echo lines. Just last night I added another field into comma delimited text file I use, and something was disturbed by it. I just uncommented few key echo lines and was able to stop what exactly was the problem.
I know it is not really pretty, but my way of thinking allowed me to reuse those echo commands, and after year or two when I try to change something, expand that database text file maybe, I will be able to debug it with lesser output deciphering.

FWIW I also have a debugging function call trace in my big scripts

Code:

#--------------------------

# Name: fct

# Purpose: function call trace (for debugging)

# $1 - name of calling function 

# $2 - message.  If it starts with "started" or "returning" then the output is prettily indented

#--------------------------

function fct {



    if [[ $debug = 'NO' ]]; then

        return 0

    fi



    fct_ident="${fct_indent:=}"



    case $2 in

        'started'* )

            fct_indent="$fct_indent  "

            call_msg 'I' "DEBUG: $fct_indent$1: $2"

            ;;

        'returning'* )

            call_msg 'I' "DEBUG: $fct_indent$1: $2"

            fct_indent="${fct_indent#  }"

            ;;

        * )

            call_msg 'I' "DEBUG: $fct_indent$1: $2"

    esac



}  # end of function fct

$debug is set by the -d option on the command line when the script is called

Code:

    debug='NO'

    while getopts c:dD:hl:r:Vw: opt 2>/dev/null

    do

        case $opt in

            {snip]

            d )

                debug='YES'

                ;;

          [snip]

        esac

    done

and call it with code like

Code:

fct "${FUNCNAME[ 0 ]}" "started with idx=$1"

and

Code:

fct "${FUNCNAME[ 0 ]}" "returning. \$dev_afn is '$dev_afn'"

Can't remember the last time I used it though!

Noted and saved to recently started bash code repository. Thanks.