保存和恢复陷阱状态？管理多个陷阱处理程序的简单方法？

有什么好的方法可以覆盖bash陷阱处理程序不会永久破坏可能已设置或尚未设置的现有处理程序？动态管理任意陷阱例程链怎么样？

有没有办法保存陷阱处理程序的当前状态，以便以后可以恢复？

在 Bash 中保存和恢复陷阱处理程序状态

我将提交以下堆栈实现来跟踪和恢复陷阱状态。使用这种方法，我可以推送陷阱更改，然后在完成后将其弹出。这也可以用于将许多陷阱例程链接在一起。

请参阅以下源文件（.trap_stack.sh）

#!/bin/bash
trap_stack_name() {
  local sig=${1//[^a-zA-Z0-9]/_}
  echo "__trap_stack_$sig"
}

extract_trap() {
  echo ${@:3:$(($#-3))}
}

get_trap() {
  eval echo $(extract_trap `trap -p $1`)
}

trap_push() {
  local new_trap=$1
  shift
  local sigs=$*
  for sig in $sigs; do
    local stack_name=`trap_stack_name "$sig"`
    local old_trap=$(get_trap $sig)
    eval "${stack_name}"'[${#'"${stack_name}"'[@]}]=$old_trap'
    trap "${new_trap}" "$sig"
  done
}

trap_pop() {
  local sigs=$*
  for sig in $sigs; do
    local stack_name=`trap_stack_name "$sig"`
    local count; eval 'count=${#'"${stack_name}"'[@]}'
    [[ $count -lt 1 ]] && return 127
    local new_trap
    local ref="${stack_name}"'[${#'"${stack_name}"'[@]}-1]'
    local cmd='new_trap=${'"$ref}"; eval $cmd
    trap "${new_trap}" "$sig"
    eval "unset $ref"
  done
}

trap_prepend() {
  local new_trap=$1
  shift
  local sigs=$*
  for sig in $sigs; do
    if [[ -z $(get_trap $sig) ]]; then
      trap_push "$new_trap" "$sig"
    else
      trap_push "$new_trap ; $(get_trap $sig)" "$sig"
    fi
  done
}

trap_append() {
  local new_trap=$1
  shift
  local sigs=$*
  for sig in $sigs; do
    if [[ -z $(get_trap $sig) ]]; then
      trap_push "$new_trap" "$sig"
    else
      trap_push "$(get_trap $sig) ; $new_trap" "$sig"
    fi
  done
}

这可以管理定义为命名函数的处理程序以及像本示例一样定义的临时例程trap "kill $!" SIGTERM SIGINT.

这是我用来帮助我编写的测试脚本：

#!/bin/bash
source .trap_stack.sh

initial_trap='echo "messy" ;'" echo 'handler'"
non_f_trap='echo "non-function trap"'
f_trap() {
  echo "function trap"
}

print_status() {
  echo "    SIGINT  trap: `get_trap SIGINT`"  
  echo "    SIGTERM trap: `get_trap SIGTERM`"
  echo "-------------"
  echo
}

echo "--- TEST START ---"
echo "Initial trap state (should be empty):"
print_status

echo 'Setting messy non-function handler for SIGINT ("original state")'
trap "$initial_trap" SIGINT
print_status

echo 'Pop empty stacks (still in original state)'
trap_pop SIGINT SIGTERM
print_status

echo 'Push non-function handler for SIGINT'
trap_push "$non_f_trap" SIGINT
print_status

echo 'Append function handler for SIGINT and SIGTERM'
trap_append f_trap SIGINT SIGTERM
print_status

echo 'Prepend function handler for SIGINT and SIGTERM'
trap_prepend f_trap SIGINT SIGTERM
print_status

echo 'Push non-function handler for SIGINT and SIGTERM'
trap_push "$non_f_trap" SIGINT SIGTERM
print_status

echo 'Pop both stacks'
trap_pop SIGINT SIGTERM
print_status

echo 'Prepend function handler for SIGINT and SIGTERM'
trap_prepend f_trap SIGINT SIGTERM
print_status

echo 'Pop both stacks thrice'
trap_pop SIGINT SIGTERM
trap_pop SIGINT SIGTERM
trap_pop SIGINT SIGTERM
print_status

echo 'Push non-function handler for SIGTERM'
trap_push "$non_f_trap" SIGTERM
print_status

echo 'Pop handler state for SIGINT (SIGINT is now back to original state)'
trap_pop SIGINT
print_status

echo 'Pop handler state for SIGTERM (SIGTERM is now back to original state)'
trap_pop SIGTERM
print_status