mjhjmtu

I want to execute a trap command in "global" scope, but the signal will come from within function. Of course it is possible to declare the variable globally beforehand or use the -g declare option. But in cases where I want to source on trap that's not very practicable as shown below:

#!/bin/bash
# ./variables
declare say=hello
declare -ri times 3

and the actual script:

#!/bin/bash
# ./trapsource

setTraps () 
 trap 'echo trap called in scope $FUNCNAME[@]; source ./variables' SIGUSR1


sourceVariables () 
 kill -SIGUSR1 $$


setTraps
sendSignal
echo I want you to $say "hello" $times times.
printf "$sayn%.0s" $(seq 1 $times)

But without declare -g NAME, thank you.

EDIT:
Is it possible to detach the kill -s USR1 $$ part completely from the current process, so that the signal comes from 'outside'?

I tried nohup and disown without success so far.

trap 'echo trap called in scope $FUNCNAME[@]; declare say=hello; declare -ri times=3' SIGUSR1

Instead of using declare -i within the trap, do that beforehand, and just assign the new value in the trap:

declare -i times=999
trap 'times=3' USR1

I think you could even use readonly times within the trap, since readonly in itself doesn't make the variable local.

E.g. this prints 1, 3, 3 and then an error modifying a readonly variable.

#!/bin/bash
trap 'readonly num=3' USR1
sub() 
 kill -USR1 $$
 echo "$num"


declare -i num=999
num=1
echo "$num"
sub
echo "$num"
num=1234

Then again, if it's the global variable you want to modify, why not use declare -g?

Is it possible to detach the kill -s USR1 $$ part completely from the current process, so that the signal comes from 'outside'?

I don't think there's a difference between a signal sent by (the builtin) kill from the script itself, and one sent by another process. As you saw, Bash seems to run the trap code in the context of the running function.

#!/bin/bash

setTraps () 
 trap 'echo trap called in scope $FUNCNAME[@]; say=hello' USR1


sendSignal () 
 kill -s USR1 "$$"


setTraps
sendSignal
printf 'I want you to %s "hello"n' "$say"

If you don't use declare at all, the trap will set the say variable to the string in global scope. The trap is still called within the scope of sendSignal scope though, but I don't think there's a way of changing that.