语法

• { } && { }这种情况下，只有左边成功执行了，右边的shell才会执行。
• { } || { }这种情况，左边shell脚本执行失败，右边才会执行，刚好可以实现try catch的功能。

背景

Bash并没有像许多编程语言中那样多的奢侈品。bash中没有try/catch;但是，可以使用&&或||实现类似的行为。

使用||：如果command1失败，则command2运行如下

command1 || command2

同样，使用&&，如果command1成功，command2将运行

try/catch的最接近的近似如下

{ # try
    command1 &&
    #save your output
} || { # catch
    # save log for exception 
}

bash也包含一些错误处理机制

set -e

如果简单命令失败，它将立即停止您的脚本。 我认为这应该是默认行为。 由于这些错误几乎总是意味着意外的事情，因此继续执行以下命令并不是“理智”。

模版

try-catch.sh

#!/bin/bash
function try(){
    [[ $- = *e* ]]; SAVED_OPT_E=$?
    set +e
}
function throw(){
    exit $1
}
function catch(){
    export ex_code=$?
    (( $SAVED_OPT_E )) && set +e
    return $ex_code
}
function throwErrors(){
    set -e
}
function ignoreErrors(){
    set +e
}

使用: sample.sh

#!/bin/bash
function try(){
    [[ $- = *e* ]]; SAVED_OPT_E=$?
    set +e
}
function throw(){
    exit $1
}
function catch(){
    export ex_code=$?
    (( $SAVED_OPT_E )) && set +e
    return $ex_code
}
function throwErrors(){
    set -e
}
function ignoreErrors(){
    set +e
}

export AnException=100
export AnotherException=101

# start with a try
try
(   # open a subshell !!!
    echo "do something"
    [ someErrorCondition ] && throw $AnException

    echo "do something more"
    executeCommandThatMightFail || throw $AnotherException

    throwErrors # automaticatly end the try block, if command-result is non-null
    echo "now on to something completely different"
    executeCommandThatMightFail

    echo "it's a wonder we came so far"
    executeCommandThatFailsForSure || true # ignore a single failing command

    ignoreErrors # ignore failures of commands until further notice
    executeCommand1ThatFailsForSure
    local result = $(executeCommand2ThatFailsForSure)
    [ result != "expected error" ] && throw $AnException # ok, if it's not an expected error, we want to bail out!
    executeCommand3ThatFailsForSure

    echo "finished"
)
# directly after closing the subshell you need to connect a group to the catch using ||
catch || {
    # now you can handle
    case $ex_code in
        $AnException)
            echo "AnException was thrown"
        ;;
        $AnotherException)
            echo "AnotherException was thrown"
        ;;
        *)
            echo "An unexpected exception was thrown"
            throw $ex_code # you can rethrow the "exception" causing the script to exit if not caught
        ;;
    esac
}

参考链接

• https://gist.github.com/e7d/e43e6586c1c2ecb67ae2
• https://www.xmodulo.com/catch-handle-errors-bash.html