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I am trying to make a script that runs 2 commands in a for loop as can be seen below:

#!/bin/bash for ((i=0; i<2; i++)); do sudo ./bin/llc test-rx -c 184 sleep 5 trap ctrl_c INT function ctrl_c() { echo "Trap: CTRL+C received, exit" exit } sudo ./bin/llc rxphylast done

The 1st command (test-rx) continues to run as its is executed and it is stopped by pressing Ctrl+C. I want to stop this command in bash script so I used trap function as can be seen in the code. But when I execute the script, 1st command is running until I press Ctrl+C and then 2nd command (rxphylast) executes. So, in my case trap function is not working. Any advice on how to stop the 1st command in the script?

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  1. Define the function and set the trap outside of the loop
  2. Define the function before you use it.

Try:

#!/bin/bash function ctrl_c() ( { echo "Trap: CTRL+C received, exit" exit } trap ctrl_c INT for ((i=0; i<2; i++)); do sudo ./bin/llc test-rx -c 184 sleep 5 sudo ./bin/llc rxphylast done

Another example, not using ./bin/llc:

#!/bin/bash function ctrl_c() { echo "Trap: CTRL+C received, exit" exit } trap ctrl_c INT for ((i=0; i<2; i++)); do echo first program sudo find / -type f > /dev/null sleep 5 echo second program sudo find / -type f > /dev/null done

Press Ctrl-C while the first find is running and it will print the "Trap: CTRL+C received, exit" message and exit immediately. Press Ctrl-C while the second find is running and it will do the same. This works the same whether sudo is used with the find commands or not - I only put that in there to make sure it wasn't sudo trapping and eating the Ctrl-C.

This is what happens when you run it and press Ctrl-C while the first find is running:

$ ./trap.sh first program ^CTrap: CTRL+C received, exit $
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  • Well, it didn't work. Its the same I have to stop by using Ctrl+C Commented Apr 8, 2021 at 11:29
  • does ./bin/llc also trap SIGINT? The script works exactly as expected if i use other programs (like find / > /dev/null, I tested this with and without sudo) instead of llc. Commented Apr 8, 2021 at 12:05
  • I had to use ./bin/llc otherwise the commands test-rx and rxphylast will not work. Could u send me ur code with other programs? Commented Apr 8, 2021 at 12:12
  • Hi Cas, I tried the new program code that u wrote. Its working fine. ./bin is the location where llc shared library is present and using this llc i can use various commands like test-rx, rxphylast etc. May be its the issue of path ./bin/llc Commented Apr 8, 2021 at 12:35
  • It's not (and can't be) the path ./bin. It might be the program llc. All evidence so far points to that. Commented Apr 8, 2021 at 12:51

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