如何从另一个 shell 脚本的数组变量替换一个 shell 脚本的数组变量？

Question

I have two shell scripts, fruits_original.sh and appending_fruits.sh . In the fruits_original.sh I have one array variable: fruits=('Apple' 'Mango' 'Guava') .

What I want to do is I have to write a shell script appending_fruits.sh that will take an argument some new fruits name is Orange and will append that new fruit name to the fruits_original.sh fruits array variable.

After script run fruits array should be remain an array only and its value should be fruits=('Apple' 'Mango' 'Guava' 'Orange') .

The file fruits_original.sh has this. Below is the appending_fruits.sh script by this my variable is changing into this fruits= ('Apple' 'Mango' 'Guava' 'Orange') . But when I am trying to do echo "${fruits[@]}" I am getting this error:

line 1: syntax error near unexpected token `('

Any luck?

fruits= ('Apple' 'Mango' 'Guava') 
echo "${fruits[@]}"

    declare -a var=$(awk -F'=' '/^fruits=/ {print $2}' fruits_original.sh)
    echo "${var[@]}"
    var[${#var[@]}]='Orange'
    joined=$(printf " '%s'" "${var[@]}")
    echo ${joined:1}
    echo "${joined[@]}"
    sed -i "s/fruits=.*/fruits= ($( echo ${joined:1})) /" fruits_original.sh

Answer 1

Do not modify the script file. Instead, create another file and source the dynamic data from it. I have chosen the location of configuration to be in /tmp directory.

# fruits_original.sh
fruits=()
if [[ -e /tmp/fruits_original.rc ]]; then
        . /tmp/fruits_original.rc 
fi
some stuff

Then generate the config file. Use declare -p to safely output properly quoted variables.

# appending_fruits.sh
fruits=()
if [[ -e /tmp/fruits_original.rc ]]; then
        . /tmp/fruits_original.rc 
fi   
fruits+=("new fruit")
decalre -p fruits > /tmp/fruits_original.rc

---

Put a uuid inside fruits_original.sh to recognize where is your snippet that you want to work with.

# fruits_original.sh

# snip 419d0df3-5f08-4511-ad5a-ad24db45aa6c
fruits=()
# snip 419d0df3-5f08-4511-ad5a-ad24db45aa6c

some stuff

Then extract the relevant parts with sed or other tool, declare "$part" it into a variable, append normally and then capture output from declare -p and replace the content between the marks again.

---

If not going with any of the above and this is only a very toy example to test some stuff, you could:

# read the line from another script
declare "$(sed '/fruits=/!d' fruits_original.sh)"
# append element
fruits+=(Orange)
# create source-able output
new="$(declare -p fruits)"
# remove declare -- in front
new="fruits=${new%*fruits=}"
# Replace the line with declare -p output.
sed -i "s/fruits=.*/fruits=$new/" fruits_original.sh

---

Notes:

• var[${#var[@]}]='Orange' - just var+=(Orange) . No need for ${# .
• $( echo ${joined:1}) is a useless use of echo (unless you want word splitting and filename expansion).
• check your scripts with https://shellcheck.net
• fruits= ( is not an assignment and will run a subshell and could cause syntax error. There is no space in assignment around = .
• declare -a var=$( - var is not an array (or, it's an array with one element).