Use this tag for questions about the `trap` Bash built-in.
Questions tagged [bash-trap]
171 questions
3
votes
1 answer
bash trap EXIT $LINENO always 1
test.sh
#!/bin/bash
set -e
trap 'echo $LINENO' EXIT
/bin/false
run
$ ./test.sh
1
How may I get the actual line number of "/bin/false" instead of always '1'?
Darren Ng
- 373
- 5
- 12
3
votes
1 answer
Trap signals both in script and subshells
I know there's a lot of questions similar to mine, but I didn't found any about trapping signals sent when a subshell is taking place on the terminal. Let me explain:
#!/bin/sh
trap 'echo "exiting.."; exit 0;' INT
var1=$(echo "ab\nab" |…
Teodoro
- 1,194
- 8
- 22
3
votes
2 answers
SIGPIPE due to file descriptors and process substitution
I am trying to save some logs from bash functions which execute tools (some of them run in subshells). In addition I would like to print all errors to the terminal.
My code leads to a sigpipe and exit code 141 upon hitting ctr-c plus a strange log…
pyr0
- 377
- 1
- 14
3
votes
2 answers
Trap with external call in command substitution breaks the parent Bash shell
I have a text-based user interface script that allows me to browse directories and select a file. The graphics are output to stderr, the chosen file's path is sent to stdout. This allows to get the chosen file this way:
file="$(./script)"
This is…
Informancien
- 255
- 3
- 13
3
votes
1 answer
SIGCHLD not delivered when a process exits
I need to detect when one of my background processes exits. Hence, I installed a trap. run_gui and run_ai1 are simple exec functions.
run_gui & gui_pid=$!
run_ai1 & ai1_pid=$!
trap 'echo foo' SIGCHLD
while true; do
echo "Started the loop"
…
marmistrz
- 5,974
- 10
- 42
- 94
3
votes
1 answer
Clean exit from bashscript which uses read and trap
Run the below script
Press Ctrl+C
Observe the current terminal behaviour.
Press enter few times and try to execute some commands.
#!/bin/bash
LOCK_FILE=/tmp/lockfile
clean_up(){
# Perform program exit housekeeping
echo -e "Signal Trapped,…
Dipankar
- 141
- 2
- 9
3
votes
3 answers
Why does my bash script take so long to respond to kill when it runs in the background?
(Question revised, now that I understand more about what's actually happening):
I have a script that runs in the background, periodically doing some work and then sleeping for 30 seconds:
echo "background script PID: $$"
trap 'echo "Exiting..."' INT…
RashaMatt
- 247
- 1
- 3
- 11
3
votes
3 answers
Why trap didn't work in a pipeline
In this script
We have a script trap.sh
#!/bin/bash
trap "echo trapped" EXIT
exit 0
and test.sh. If test.sh is like
#!/bin/bash
. trap.sh
or
#!/bin/bash
./trap.sh | :
trap works
But if test.sh is like
#!/bin/bash
. trap.sh | :
the trap didn't…
dspjm
- 5,473
- 6
- 41
- 62
3
votes
1 answer
bash shell: Can a control-c cause shell to write an empty file?
I have a bash shell script. It writes out to a text file. Most of the it works find if I stop the script with a control-c at the command level. Sometimes the file that's been written to such as
echo "hello world" >myfile.txt
will end up being…
Edward
- 9,430
- 19
- 48
- 71
3
votes
3 answers
How to keep restarting a Windows cmd prompt
Cygwin's bash is often preferable to Windows' cmd command shell, so we use it to set up our environments before spawning a Windows shell. However, halting execution of a running process in this spawned shell with Ctrl-C kills boots the user back to…
tcdaniel
- 203
- 1
- 2
- 11
3
votes
1 answer
bash send errors by email
I wrote some bash script that does some backup job. I run the script with errexit and pipefail so I won't miss any error. The thing I want now is the script sending me an email in case an error occures. I got this working. But I want the scripts…
Mike Dynamite
- 65
- 2
- 8
3
votes
2 answers
how to trap errors inside the if statement
Running the following code:
#!/bin/bash
set -o pipefail
set -o errtrace
set -o nounset
set -o errexit
function err_handler ()
{
local error_code="$?"
echo "TRAP!"
echo "error code: $error_code"
exit
}
trap err_handler ERR
echo…
Luca Borrione
- 16,324
- 8
- 52
- 66
2
votes
1 answer
Perl trapping Ctrl-C (sigint) in bash
I'm reading How do we capture CTRL ^ C - Perl Monks, but I cannot seem to get the right info to help with my problem.
The thing is - I have an infinite loop, and 'multiline' printout to terminal (I'm aware I'll be told to use ncurses instead - but…
sdaau
- 36,975
- 46
- 198
- 278
2
votes
0 answers
redirecting stderr to err function
I want to trap errors with my err function, which writes to the stderr. But in this example I am getting two error lines. How can I remove the first error msg not generated by my err function? I want to prevent something like
_get_error_msg 2>…
mikee
- 29
- 3
2
votes
1 answer
Trap Command not detecting terminal resize (SIGWINCH)
Im trying to detect when my menu is resized using trap "echo resized" SIGWINCH but it doesnt seem to be detecting it. Im currently using ubuntu 20.04 and i am using a bash script to do this.
The trap command is at the top of my script. Why is it not…
Quantum
- 59
- 5