multiple bash traps for the same signal

Question

When I use the trap command in bash, the previous trap for the given signal is replaced.

Is there a way of making more than one trap<

Answer 1

No

About the best you could do is run multiple commands from a single trap for a given signal, but you cannot have multiple concurrent traps for a single signal. For example:

$ trap "rm -f /tmp/xyz; exit 1" 2
$ trap
trap -- 'rm -f /tmp/xyz; exit 1' INT
$ trap 2
$ trap
$

The first line sets a trap on signal 2 (SIGINT). The second line prints the current traps — you would have to capture the standard output from this and parse it for the signal you want. Then, you can add your code to what was already there — noting that the prior code will most probably include an 'exit' operation. The third invocation of trap clears the trap on 2/INT. The last one shows that there are no traps outstanding.

You can also use trap -p INT or trap -p 2 to print the trap for a specific signal.