是否有存储和计算返回值的bash脚本优雅的方式？ [英] Is there an elegant way to store and evaluate return values in bash scripts?

问题描述

我有一个相当复杂的一系列bash中的最终返回一个有意义的退出code命令。各个地方在后面的脚本需要分支有条件的命令集成功与否。

I have a rather complex series of commands in bash that ends up returning a meaningful exit code. Various places later in the script need to branch conditionally on whether the command set succeed or not.

目前我储存的退出code和数字测试它，像这样：

Currently I am storing the exit code and testing it numerically, something like this:

long_running_command | grep -q trigger_word
status=$?

if [ $status -eq 0 ]; then
    : stuff
else

: more code

if [ $status -eq 0 ]; then
    : stuff
else

出于某种原因，感觉这应该是简单。我们有一个存储简单的退出code，现在我们正在重复输入了数值实验操作在其上运行。例如，我能骗来代替返回code这是简单的测试字符串输出：

For some reason it feels like this should be simpler. We have a simple exit code stored and now we are repeatedly typing out numerical test operations to run on it. For example I can cheat use the string output instead of the return code which is simpler to test for:

status=$(long_running_command | grep trigger_word)

if [ $status ]; then
    : stuff
else

: more code

if [ $status ]; then
    : stuff
else

在表面上，这看起来更直截了当，但我意识到这是脏的。

On the surface this looks more straight forward, but I realize it's dirty.

如果其他的逻辑是没有那么复杂，我只是跑这个曾经，我知道我可以代替测试运营商的嵌入，但是当你需要重复使用在其他位置的结果<强这是不理想>不必重新运行测试

If the other logic wasn't so complex and I was only running this once, I realize I could embed it in place of the test operator, but this is not ideal when you need to reuse the results in other locations without re-running the test:

if long_running_command | grep -q trigger_word; then
    : stuff
else

我到目前为止发现的唯一的事情就是为命令替换的一部分分配code：

The only thing I've found so far is assigning the code as part of command substitution:

status=$(long_running_command | grep -q trigger_word; echo $?)

if [ $status -eq 0 ]; then
    : stuff
else

即使这不是技术上的一次性分配（虽然有些人可能认为可读性更好），但必要的数值试验语法似乎仍然很麻烦给我。也许我只是强迫症。

Even this is not technically a one shot assignment (although some may argue the readability is better) but the necessary numerical test syntax still seems cumbersome to me. Maybe I'm just being OCD.

我失去了一个更优雅的方式来分配出口code到一个变量再后来就IT部门？

推荐答案

简单的解决方案：

output=$(complex_command)
status=$?

if (( status == 0 )); then
    : stuff with "$output"
fi

: more code

if (( status == 0 )); then
    : stuff with "$output"
fi

或者更eleganter十岁上下

Or more eleganter-ish

do_complex_command () { 
    # side effects: global variables
    # store the output in $g_output and the status in $g_status
    g_output=$(
        command -args | commands | grep -q trigger_word
    )
    g_status=$?
}
complex_command_succeeded () {
    test $g_status -eq 0
}
complex_command_output () {
    echo "$g_output"
}

do_complex_command

if complex_command_succeeded; then
    : stuff with "$(complex_command_output)"
fi

: more code

if complex_command_succeeded; then
    : stuff with "$(complex_command_output)"
fi

或者

do_complex_command () { 
    # side effects: global variables
    # store the output in $g_output and the status in $g_status
    g_output=$(
        command -args | commands
    )
    g_status=$?
}
complex_command_output () {
    echo "$g_output"
}
complex_command_contains_keyword () {
    complex_command_output | grep -q "$1"
}

if complex_command_contains_keyword "trigger_word"; then
    : stuff with "$(complex_command_output)"
fi

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