在我的程序中，按照约定，这就是预先存在的$REPLY变量的用途，read正是为此目的而使用它。

function getSomeString {
  REPLY="tadaa"
}

getSomeString
echo $REPLY

这种回声

tadaa

但是为了避免冲突，任何其他全局变量都可以。

declare result

function getSomeString {
  result="tadaa"
}

getSomeString
echo $result

如果这还不够，我推荐Markarian451的解决方案。

如前所述，从函数返回字符串的“正确”方法是使用命令替换。如果函数也需要输出到控制台(如@Mani上面提到的)，在函数的开头创建一个临时fd并重定向到控制台。在返回字符串之前关闭临时fd。

#!/bin/bash
# file:  func_return_test.sh
returnString() {
    exec 3>&1 >/dev/tty
    local s=$1
    s=${s:="some default string"}
    echo "writing directly to console"
    exec 3>&-     
    echo "$s"
}

my_string=$(returnString "$*")
echo "my_string:  [$my_string]"

执行没有参数的脚本会产生…

# ./func_return_test.sh
writing directly to console
my_string:  [some default string]

希望这能帮助到人们

安迪

提醒薇姬·罗嫩，考虑一下下面的代码

function use_global
{
    eval "$1='changed using a global var'"
}

function capture_output
{
    echo "always changed"
}

function test_inside_a_func
{
    local _myvar='local starting value'
    echo "3. $_myvar"

    use_global '_myvar'
    echo "4. $_myvar"

    _myvar=$( capture_output )
    echo "5. $_myvar"
}

function only_difference
{
    local _myvar='local starting value'
    echo "7. $_myvar"

    local use_global '_myvar'
    echo "8. $_myvar"

    local _myvar=$( capture_output )
    echo "9. $_myvar"
}

declare myvar='global starting value'
echo "0. $myvar"

use_global 'myvar'
echo "1. $myvar"

myvar=$( capture_output )
echo "2. $myvar"

test_inside_a_func
echo "6. $_myvar" # this was local inside the above function

only_difference

将会给

0. global starting value
1. changed using a global var
2. always changed
3. local starting value
4. changed using a global var
5. always changed
6. 
7. local starting value
8. local starting value
9. always changed

也许正常的场景是使用test_inside_a_func函数中使用的语法，因此在大多数情况下可以同时使用这两种方法，尽管捕获输出是在任何情况下都能工作的更安全的方法，它模仿在其他语言中可以找到的函数的返回值，Vicky Ronnen正确地指出了这一点。

虽然有很多很好的答案，但它们都不是我想要的方式。下面是我的解决方案，要点如下:

帮助健忘的程序员

至少我会努力记住错误检查之后，像这样:

允许用换行字符\n赋值

有些解决方案不允许这样做，因为有些解决方案忘记了要赋值周围的单引号。正确的方法:eval "${returnVariable}='${value}'"或者更好:参见下面的下一点。

使用printf代替eval

只需尝试使用类似myFunction "date && var2"的东西来解决这里的一些假定的解决方案。Eval会执行给它的任何东西。我只想分配值，所以我使用printf -v "${returnVariable}" "%s" "${value}"代替。

对变量名冲突的封装和保护

如果一个不同的用户或至少是对函数了解较少的人(这可能是几个月后的我)正在使用myFunction，我不希望他们知道他必须使用全局返回值名称或禁止使用某些变量名称。这就是为什么我在myFunction的顶部添加了一个名称检查:

    if [[ "${1}" = "returnVariable" ]]; then
        echo "Cannot give the ouput to \"returnVariable\" as a variable with the same name is used in myFunction()!"
        echo "If that is still what you want to do please do that outside of myFunction()!"
        return 1
    fi

注意，如果你需要检查很多变量，这也可以放在函数本身中。 如果我仍然想使用相同的名称(这里:returnVariable)，我只是创建了一个缓冲变量，给myFunction，然后复制值returnVariable。

就是这样:

myFunction ():

myFunction() {
    if [[ "${1}" = "returnVariable" ]]; then
        echo "Cannot give the ouput to \"returnVariable\" as a variable with the same name is used in myFunction()!"
        echo "If that is still what you want to do please do that outside of myFunction()!"
        return 1
    fi
    if [[ "${1}" = "value" ]]; then
        echo "Cannot give the ouput to \"value\" as a variable with the same name is used in myFunction()!"
        echo "If that is still what you want to do please do that outside of myFunction()!"
        return 1
    fi
    local returnVariable="${1}"
    local value=$'===========\nHello World\n==========='
    echo "setting the returnVariable now..."
    printf -v "${returnVariable}" "%s" "${value}"
}

测试用例:

var1="I'm not greeting!"
myFunction var1
[[ $? -eq 0 ]] && echo "myFunction(): SUCCESS" || echo "myFunction(): FAILURE"
printf "var1:\n%s\n" "${var1}"

# Output:
# setting the returnVariable now...
# myFunction(): SUCCESS
# var1:
# ===========
# Hello World
# ===========

returnVariable="I'm not greeting!"
myFunction returnVariable
[[ $? -eq 0 ]] && echo "myFunction(): SUCCESS" || echo "myFunction(): FAILURE"
printf "returnVariable:\n%s\n" "${returnVariable}"

# Output
# Cannot give the ouput to "returnVariable" as a variable with the same name is used in myFunction()!
# If that is still what you want to do please do that outside of myFunction()!
# myFunction(): FAILURE
# returnVariable:
# I'm not greeting!

var2="I'm not greeting!"
myFunction "date && var2"
[[ $? -eq 0 ]] && echo "myFunction(): SUCCESS" || echo "myFunction(): FAILURE"
printf "var2:\n%s\n" "${var2}"

# Output
# setting the returnVariable now...
# ...myFunction: line ..: printf: `date && var2': not a valid identifier
# myFunction(): FAILURE
# var2:
# I'm not greeting!

myFunction var3
[[ $? -eq 0 ]] && echo "myFunction(): SUCCESS" || echo "myFunction(): FAILURE"
printf "var3:\n%s\n" "${var3}"

# Output
# setting the returnVariable now...
# myFunction(): SUCCESS
# var3:
# ===========
# Hello World
# ===========

以上所有答案都忽略bash手册页中所述内容。

函数中声明的所有变量都将与调用环境共享。 所有在本地声明的变量将不会被共享。

示例代码

#!/bin/bash

f()
{
    echo function starts
    local WillNotExists="It still does!"
    DoesNotExists="It still does!"
    echo function ends
}

echo $DoesNotExists #Should print empty line
echo $WillNotExists #Should print empty line
f                   #Call the function
echo $DoesNotExists #Should print It still does!
echo $WillNotExists #Should print empty line

和输出

$ sh -x ./x.sh
+ echo

+ echo

+ f
+ echo function starts 
function starts
+ local 'WillNotExists=It still does!'
+ DoesNotExists='It still does!'
+ echo function ends 
function ends
+ echo It still 'does!' 
It still does!
+ echo

同样在pdksh和ksh下，这个脚本也做同样的事情!

您还可以捕获函数输出:

#!/bin/bash
function getSomeString() {
     echo "tadaa!"
}

return_var=$(getSomeString)
echo $return_var
# Alternative syntax:
return_var=`getSomeString`
echo $return_var

看起来很奇怪，但比使用全局变量更好。传递参数和往常一样，只是把它们放在大括号或反勾号内。