Use this tag for questions about the `trap` Bash built-in.
Questions tagged [bash-trap]
171 questions
7
votes
1 answer
bash trap of TERM - what am I doing wrong?
Given this hack.c program:
#include
main()
{
int i=0;
for(i=0; i<100; i++) {
printf("%d\n", i);
sleep(5);
}
}
and this hack.sh bash script:
#!/bin/bash
./hack
If I run hack.sh, two processes get created - one for bash, one for…
user185094
6
votes
2 answers
Reliably kill sleep process after USR1 signal
I am writing a shell script which performs a task periodically and on receiving a USR1 signal from another process.
The structure of the script is similar to this answer:
#!/bin/bash
trap 'echo "doing some work"' SIGUSR1
while :
do
sleep 10…
jameh
- 1,149
- 3
- 12
- 20
6
votes
3 answers
Trying to close all child processes when I interrupt my bash script
I have written a bash script to carry out some tests on my system. The tests run in the background and in parallel. The tests can take a long time and sometimes I may wish to abort the tests part way through.
If I Control+C then it aborts the parent…
aghsmith
- 265
- 3
- 11
6
votes
2 answers
ctrl+c to kill a bash script with child processes
I have a script whose internals boil down to:
trap "exit" SIGINT SIGTERM
while :
do
mplayer sound.mp3
sleep 3
done
(yes, it is a bit more meaningful than the above, but that's not relevant to the problem). Several instances of the script…
18446744073709551615
- 16,368
- 4
- 94
- 127
6
votes
1 answer
Bash: Trap ERR does not work when pipe operator is used
I am trying to log everything that comes out of stdout and stderr into a log file and still preserve the console. For this, I just appended: |& tee -a log_file.log to every command.
However, I also want to run a custom command if any error occurred…
cristiprg
- 103
- 1
- 9
5
votes
3 answers
Bash, CTRL+C in eval not interrupting the main script
In my bash script, I'm running an external command that's stored in $cmd variable. (It could be anything, even some simple bash oneliner.)
If ctrl+C is pressed while running the script, I want it to kill the currently running $cmd but it should…
Miroslav
- 528
- 1
- 6
- 11
5
votes
2 answers
How do I trap SIGQUIT properly in a bash script?
I can write shell scripts that trap SIGINT just fine, but I can't seem to trap SIGQUIT.
#!/bin/bash
function die {
echo "Dying on signal $1"
exit 0
}
trap 'die "SIGINT"' SIGINT
trap 'die "SIGQUIT"' SIGQUIT
while true; do
echo…
Maxy-B
- 2,772
- 1
- 25
- 33
5
votes
1 answer
Unable to trap signals in docker entrypoint script
I have a docker entrypoint script that is supposed to trap signals sent to processes in the container. The main application is tomcat - java process embedded in the docker-entrypoint.sh which is passed to dumb-init. The process mapping in the…
IPlato
- 191
- 2
- 7
5
votes
1 answer
Bash function scope status when EXIT trap is executed after a program exits with status != 0 (set -e)
Declaring a local variable in a bash function makes that variable only visible inside the function itself and its children, so if I run:
#!/bin/bash
set -e
func_one() {
echo "${var}"
}
func_two() {
local -r var="var from func_two"
…
Egidio Docile
- 117
- 6
5
votes
2 answers
Bash Trap: How to Get Line Number of a Subprocess with Non-Zero Status
For the Bash program:
1 #!/bin/bash
2
3 trapinfo()
4 {
5 echo "=== Trap Info: Status=$? LINENO=$@ A=$A"
6 }
7
8 main()
9 {
10 trap 'trapinfo $LINENO -- ${BASH_LINENO[*]}' ERR
11
12 set -e
13 set -E
14 set -o…
Steve Amerige
- 1,309
- 1
- 12
- 28
5
votes
1 answer
Where does the exit status go after trap/return?
I was playing around with using trap inside a function because of this question, and came up with this secondary question. Given the following code:
d() {
trap 'return' ERR
false
echo hi
}
If I run d, the trap causes the shell to return…
kojiro
- 74,557
- 19
- 143
- 201
5
votes
1 answer
How to trap on_error in bash globally?
It seems on_error trap in Bash works only in the scope of function it was defined in. For instance running this script
#!/bin/bash
on_error() {
echo 'on_error'
}
f() {
false
echo 'function f'
}
g() {
trap on_error ERR
echo…
Piotr Dobrogost
- 41,292
- 40
- 236
- 366
4
votes
2 answers
Restore traps without a temp file
Without arguments trap prints the currently set commands for all traps. However, a subshell does not inherit traps, so the canonical example for saving and restoring traps fails in bash:
save_traps=$(trap)
...
eval "$save_traps"
The trap on the…
William Pursell
- 204,365
- 48
- 270
- 300
4
votes
2 answers
`ERR` trap is not executed when syntax error
According to man bash,
set -e
Exit immediately if (snip). A trap on ERR, if set, is executed before the shell exits.
However, the script below doesn't invoke the ERR trap.
trap 'echo ERR; sleep 1' ERR
trap 'echo EXIT; sleep 1' EXIT
set…
ynn
- 3,386
- 2
- 19
- 42
4
votes
3 answers
How to get return code in TRAP ... RETURN?
This is my code:
function my::return() {
exit_code="$1"
echo "exit status of last command: ${exit_code}"
}
function testing(){
trap 'my::return $?' RETURN
return 2
}
If I run testing I expect the exit_code to be 2 as tyhis is the…
Stefan Thorpe
- 540
- 1
- 4
- 11