Question

when I am working on shell script, I am little frusturate on $@ and “$@” problem. So, I write a shell script to do some testing. like following.

func()
{
    local a="$@"
    for i in "$a";  do
        echo "$i ****"
    done
}

func000()
{
    local a="$@"
    for i in $a;  do
        echo "$i ****"
    done
}

func0()
{
    local a=$@
    for i in "$a";  do
            echo "$i ****"
    done
}

func00()
{
    local a=$@
    for i in $a;  do
        echo "$i ****"
    done
}

func1()
{
    for i in "$@";  do
        echo "$i ****"
    done
}

func2() 
{
    for i in $@;  do
        echo "$i ****"
    done
}

func "a b c"
func a b c 

echo "-----------"
func0 "a b c"
func0 a b c 

echo "-----------"
func00 "a b c"
func00 a b c 

echo "-----------"
func000 "a b c"
func000 a b c 

echo "-----------"
func1 "a b c"
func1 a b c 

echo "-----------"
func2 "a b c"
func2 a b c 




a b c ****
a b c ****   func
-----------
a b c ****   func0
a b c ****
-----------
a ****       func00
b ****
c ****
a ****
b ****
c ****
------------
a ****   func000
b ****
c ****
a ****
b ****
c ****

-----------
a b c ****     func1   //this has the result that I want. 
a **** 
b ****
c ****
----------- 
a ****      func2
b ****
c ****
a ****
b ****
c ****

As far as I remember, when using $@, we have to use double quoate, otherwise something will break. Therefore, I know some of functions definitely not work properly. (I still test it anyway)

Only func1 gives me a desire result, however, the thing is I want to assign “$@” to a variable. by reviewing func0, func000, func0, func00 results, none of those give me correct stuff. So, I am hoping someone can help me out.

In addition, I know sh and bash has difference. If someone can point me out in which condition something could break I will be so glad. Thanks.

---

update

I should say, this result of this script, it comes to the version of bash or sh, or freebsd sh vs linux sh.

I could be wrong, if so, just point it out, thanks a lot.

in old sh, freebsd sh, in which we do not have array, obviously, array assignment could not get working, the alternative is to use string like what I did in func000, local a=”$a”; for i in $a; do …

If using linux sh 4.5 (tested), or bash, see my answer below.

Answer 1

---

update, thanks to @jordanm, I realize this is the difference between bash and old sh version somehow.

this is a solution in bash or sh 4.2. in old sh, this might not be working.

  33 func3()                                                                         
  34 {                                                                               
  35     local a=("${@}")                                                            
  36                                                                                 
  37     for i in "${a[@]}"; do                                                      
  38         echo "$i ****"                                                          
  39     done                                                                        
  40 }