bash-trap

问题 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 "wrong command in if statement" if xsxsxsxs then echo "if result is true" else echo "if result is false" fi echo -e "\nwrong command directly" xsxsxsxs exit produces the following output: wrong command in if statement trap.sh: line 21: xsxsxsxs: command not found if

问题 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 "wrong command in if statement" if xsxsxsxs then echo "if result is true" else echo "if result is false" fi echo -e "\nwrong command directly" xsxsxsxs exit produces the following output: wrong command in if statement trap.sh: line 21: xsxsxsxs: command not found if

问题 I'm using this script to test trap: #!/bin/bash trap "echo segfault!" SIGSEGV g++ forever.cpp ./a.out And forever.cpp just runs a recursive function: void forever(){ forever(); } int main(){ forever(); } However it gives Segmentation fault: 11 instead of printing segfault . I'm not sure why. 回答1: The trap statement traps signals received by bash , not its children. The child receives the segfault and will be exiting with an appropriate exit code. You should therefore check the exit code from

问题 Please consider this bash-script: #!/bin/bash trap '' INT echo sleep: sleep 5 echo rsync: rsync -a /usr/lib /var/tmp Trying to interrupt sleep with ctrl-c fails, as expected. But rsync is interruptible (the order of sleep & rsync doesn't matter)? Any ideas are welcome! Edit: Found a difference: rsync itself starts 2 child procs (client/server, which produce the 2 error msgs, i assume), and these seem not to inherit the 'ignorance' of its parent. Must dive into bash sources and find out how

问题 Please consider this bash-script: #!/bin/bash trap '' INT echo sleep: sleep 5 echo rsync: rsync -a /usr/lib /var/tmp Trying to interrupt sleep with ctrl-c fails, as expected. But rsync is interruptible (the order of sleep & rsync doesn't matter)? Any ideas are welcome! Edit: Found a difference: rsync itself starts 2 child procs (client/server, which produce the 2 error msgs, i assume), and these seem not to inherit the 'ignorance' of its parent. Must dive into bash sources and find out how

问题 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 && echo "doing some work" & wait $! done However, this script has the problem that the sleep process continues in the background and only dies on its timeout. (note that when USR1 is received during wait $!, the sleep process lingers for its regular

问题 On Linux, is it possible to somehow disable signaling for programs externally ... that is, without modifying their source code? Context: I'm calling a C ( and also a Java ) program from within a bash script on Linux. I don't want any interruptions for my bash script, and for the other programs that the script launches (as foreground processes). While I can use a... trap '' INT ... in my bash script to disable the Ctrl C signal, this works only when the program control happens to be in the

问题 Here is minimal code for issue demonstration: http://pastebin.com/5TXDpSh5 #!/bin/bash set -e set -o pipefail function echoTraps() { echo "= on start:" trap -p trap -- 'echo func-EXIT' EXIT echo "= after set new:" trap -p # we can ensure after script done - file '/tmp/tmp.txt' was not created trap -- 'echo SIG 1>/tmp/tmp.txt' SIGPIPE SIGHUP SIGINT SIGQUIT SIGTERM } trap -- 'echo main-EXIT1' EXIT echo "===== subshell trap" ( echoTraps; ) echo "===== pipe trap" echoTraps | cat echo "===== done

问题 I have a bash script that mounts and unmounts a device, which performing some read operations in between. Since the device is very slow, the script takes about 15 seconds to complete (the mount taking atleast 5-6 seconds). Since leaving this device mounted can cause other problems, I don't want this script to be interrupted. Having said that, I can correctly handle SIGINT (Ctrl+c), but when I try to handle SIGTSTP (Ctrl+z), the script freezes. Which means the signal is trapped but the handler

问题 I am unable to trap a signal when running in a child / background process. Here is my simple bash script : #!/bin/bash echo "in child" trap "got_signal" SIGINT function got_signal { echo "trapped" exit 0 } while [ true ]; do sleep 2 done When running this and later do kill -SIGINT (pid) Everything works as expected, it prints 'trapped' and exits. Now, if I start the same script from a parent script like this : #!/bin/bash echo "starting the child" ./child.sh & Then the child does not trap the