![访问关联数组的值,其名称作为 bash 函数内的参数传递](https://linux22.com/image/225026/%E8%AE%BF%E9%97%AE%E5%85%B3%E8%81%94%E6%95%B0%E7%BB%84%E7%9A%84%E5%80%BC%EF%BC%8C%E5%85%B6%E5%90%8D%E7%A7%B0%E4%BD%9C%E4%B8%BA%20bash%20%E5%87%BD%E6%95%B0%E5%86%85%E7%9A%84%E5%8F%82%E6%95%B0%E4%BC%A0%E9%80%92.png)
我在 bash 脚本中有一些关联数组,我需要将它们传递给一个函数,在该函数中我还需要访问键和值。
declare -A gkp=( \
["arm64"]="ARM-64-bit" \
["x86"]="Intel-32-bit" \
)
fv()
{
local entry="$1"
echo "keys: ${!gkp[@]}"
echo "vals: ${gkp[@]}"
local arr="$2[@]"
echo -e "\narr entries: ${!arr}"
}
fv $1 gkp
上述输出:
kpi: arm64 x86
kpv: ARM-64-bit Intel-32-bit
arr entries: ARM-64-bit Intel-32-bit
我可以获取传递给函数的数组值,但无法弄清楚如何在函数中打印键(即“arm64”“x86”)。
请帮忙。
答案1
您需要将arr
变量设置为 nameref。从man bash
:
A variable can be assigned the nameref attribute using the -n option
to the declare or local builtin commands (see the descriptions of de‐
clare and local below) to create a nameref, or a reference to another
variable. This allows variables to be manipulated indirectly. When‐
ever the nameref variable is referenced, assigned to, unset, or has
its attributes modified (other than using or changing the nameref at‐
tribute itself), the operation is actually performed on the variable
specified by the nameref variable's value. A nameref is commonly used
within shell functions to refer to a variable whose name is passed as
an argument to the function. For instance, if a variable name is
passed to a shell function as its first argument, running
declare -n ref=$1
inside the function creates a nameref variable ref whose value is the
variable name passed as the first argument. References and assign‐
ments to ref, and changes to its attributes, are treated as refer‐
ences, assignments, and attribute modifications to the variable whose
name was passed as $1. If the control variable in a for loop has the
nameref attribute, the list of words can be a list of shell variables,
and a name reference will be established for each word in the list, in
turn, when the loop is executed. Array variables cannot be given the
nameref attribute. However, nameref variables can reference array
variables and subscripted array variables. Namerefs can be unset us‐
ing the -n option to the unset builtin. Otherwise, if unset is exe‐
cuted with the name of a nameref variable as an argument, the variable
referenced by the nameref variable will be unset.
实际上,这看起来像:
#!/bin/bash
declare -A gkp=(
["arm64"]="ARM-64-bit"
["x86"]="Intel-32-bit"
)
fv()
{
local entry="$1"
echo "keys: ${!gkp[@]}"
echo "vals: ${gkp[@]}"
local -n arr_name="$2"
echo -e "\narr entries: ${!arr_name[@]}"
}
fv "$1" gkp
运行它会给出:
$ foo.sh foo
keys: x86 arm64
vals: Intel-32-bit ARM-64-bit
arr entries: x86 arm64
强制性警告:如果您发现自己需要在 shell 脚本中执行类似的操作,通常强烈表明您可能想要切换到适当的脚本语言,例如 Perl 或 Python 或其他任何语言。