Getting wrong $LINENO for a trapped function

I am writing a Bash script for myself to learn scripting. At some point, I need to add trap in order to clean unwanted directories and files if script is killed. However, for some reason I do not understand, trap calls the cleaning function – clean_a() – when script killed but $LINENO points to a line in the cleaning function itself, not int the function – archieve_it() – when script is killed.

Expected behaviour:

1. run script
2. Press Ctrl+C
3. trap caches Ctrl+C and calls clean_a() function
4. clean_a() function echoes the line number, which Ctrl+C is pressed. Let it be line 10 in archieve_it().

What actually happens:

1. run script
2. Press Ctrl+C
3. trap caches Ctrl+C and calls clean_a() function
4. clean_a() echoes an irrelevant line number. Say, line 25 in clean_a() function.

Here is an example as a part of my script:

archieve_it () {
  trap 'clean_a $LINENO $BASH_COMMAND'
                SIGHUP SIGINT SIGTERM SIGQUIT
  for src in ${sources}; do
   mkdir -p "${dest}${today}${src}"
   if [[ "$?" -ne 0 ]] ; then
    error "Something!" 
   fi
   rsync "${options}" 
         --stats -i 
         --log-file="${dest}${rsync_log}" 
         "${excludes}" "${src}" "${dest}${today}${src}"
  done
}
clean_a () {
  error "something!
  line: $LINENO
  command: $BASH_COMMAND
  removing ${dest}${today}..."
  cd "${dest}"
  rm -rdf "${today}"
  exit "$1"
}

P.S.: Original script can be seen here . Definitions and variable names are in Turkish. If it is required, I can translate anything to English.

EDIT: I change the script as best as I can do according to @mikeserv’s explanation like this:

#!/bin/bash
PS4='DEBUG: $((LASTNO=$LINENO)) : '; set -x
archieve_it () {
  trap 'clean_a $LASTNO $LINENO $BASH_COMMAND'
                SIGHUP SIGINT SIGTERM SIGQUIT
  ..
}
clean_a () {
  error " ...
  line: $LINENO $LASTNO
  ..."
}

Now, if I run script with set -x and terminate it with Ctrl+C, it prints correct line number as can be seen below:

 DDEBUG: 1 : clean_a 1 336 rsync '"${options}"' ...

However, in clean_a() function, value of $LASTNO is printed as 1.

 line: 462 1

Does it have something to do with the bug that is shown by @Arkadiusz Drabczyk?

EDIT2: I changed script just like the way @mikesrv recommended to me. But $LASTNO returned 1 as the value of the line when script was terminated (it should have been 337).

#!/bin/bash
PS4='^MDEBUG: $((LASTNO=$LINENO)) : '; set -x
archieve_it () {
  trap 'clean_a $LASTNO $LINENO "$BASH_COMMAND"' 
                SIGHUP SIGINT SIGTERM SIGQUIT
  ...
} 2>/dev/null
clean_a () {
  error " ...
  line: $LASTNO $LINENO
  ..."
} 2>&1

If I run script and terminate it with Ctrl+C while rsync was running, I get this output:

^^MDEBUG: 1 : clean_a '337 1 rsync "${options}" --delete-during ...
...
line: 1 465

As you can see, $LASTNO’s value is 1.

While I was trying to figure out what the problem is, I wrote another function – testing – using parameter substitution format ${parameter:-default}. So script turned out like this:

#!/bin/bash
PS4='^MDEBUG: $((LASTNO=$LINENO)) : '; set -x
archieve_it () {
  trap 'testing "$LASTNO $LINENO $BASH_COMMAND"'
                 SIGHUP SIGINT SIGTERM SIGQUIT
  ...
} 2>/dev/null
testing() {
  echo -e "${1:-Unknown error!}"
  exit 1
} 2>&1

Now, if I run script and press Ctrl+C, I get this output:

^^MDEBUG: 1 : testing '337 1 rsync "${options}" --delete-during ...
337 1 rsync "${options}" --delete-during ... 

337 points out the line when I pressed Ctrl+C, while rsync was running.

For another test, I tried writing clear_a funtion like this:

clear_a () {
  echo -e " $LASTNO $LINENO"
}

and $LASTNO still returned 1.

So, this means that we can get correct line number when script terminated if we use parameter substitution?

EDIT3 It seems that I wrongly applied @mikeserv’s explanation in EDIT2. I corrected my mistake. Positional parameter "$1 should be replaced with $LASTNO in clear_a funtion.

Here is the script which works how I want it to work:

#!/bin/bash
PS4='^MDEBUG: $((LASTNO=$LINENO)) : '; set -x
archieve_it () {
  trap 'clean_a $LASTNO $LINENO "$BASH_COMMAND"' 
                SIGHUP SIGINT SIGTERM SIGQUIT
  ...
} 2>/dev/null
clean_a () {
  error " ...
  line: $1
  ..."
} 2>&1

When the script is terminated, trap evaluates $LASTNO – first argument -, $LINENO – second argument – and $BASH_COMMAND -third argument -, then pass their values to the clear_a function. Finally, we print $LASTNO with $1 as the line number which script is terminated.