Pass bash array to expect script

Question

I have a bash script that calls an expect script like so

$SCRIPTS_DIRECTORY/my_expect_script.sh $my_bash_array

I can pass a variable over, it seems, and use it. For this example the variable seems to be in [lindex $argv 0].

From bash, it will be a bunch of values, e.g. 1 2 3 4 5.

I am trying to figure out how to use expect to grab this variable, save it to an array then loop through the array to spit out multiple commands one at a time.

So my output should be something like

send command 1 \r
send command 2 \r

etc., until it reaches the end of the array.

I thought in expect I would assign it like

array set myArray [lindex $argv 0]

but it looks like I am wrong.

Would anyone have any good places I can look that might explain going from bash to expect better, or know how to do this? I assume its relatively simple, but expect is very iffy with me in some aspects.

If I understand correctly, you explain that you can access the variable using [lindex $argv 0]. Why, then, are you trying to use [lindex $argv 5] instead? — mkrieger1
– mkrieger1, Commented Jun 14, 2017 at 21:56
$my_bash_array only expands to the first element of an array. Maybe your "array" is really a string? — Charles Duffy
– Charles Duffy, Commented Jun 15, 2017 at 1:16
The 5 was a typo, I shortened the code from what i was using because i was passing 5 variables to the expect script and the 5th one was the one i was originally trying to access in the live code. — Rob
– Rob, Commented Jun 15, 2017 at 13:13
Take care with your expect commands: lindex returns a single element from a list; array set expects as its last argument an even-numbered list of name-value pairs. In Tcl/expect, an "array" is actually an associative array, and a "list" is a numerically-indexed array. — glenn jackman
– glenn jackman, Commented Jun 19, 2017 at 18:30

tripleee · Accepted Answer · 2020-01-09 05:35:46Z

2

Sample.sh

my_array=(1 2 3 4 5)
expect sample.exp "${my_array[@]}"

Sample.exp

foreach arg $argv { 
    puts "arg : $arg"   
}

Output :

dinesh@mypc:~$ ./sample.sh 
arg : 1
arg : 2
arg : 3
arg : 4
arg : 5
dinesh@mypc:~$

edited Jan 9, 2020 at 5:35

tripleee

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answered Jun 15, 2017 at 1:06

Dinesh

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4 Comments

Charles Duffy Over a year ago

Quotes -- "${my_array[@]}" -- are needed to ensure that my_array=( "first argument" "second argument" ) is treated distinctly from my_array=( "first" "argument" "second" "argument" ).

Rob Over a year ago

Question, If i am passing multiple values to the expect script, Would this be the correct way to call the variable? foreach variable [lindex $argv 5]{ puts "variable equals : $variable" } I,m guessing there is a different way to do it since i am getting this error code wrong # args: should be "foreach varList list ?varList list ...? command" while executing "foreach variable [lindex $argv 5]{"

Rob Over a year ago

As an update, i was able to get it to pass the variable correctly, but it still gives the error code wrong # args: should be "foreach varList list ?varList list ...? command" code while trying to pass a variable "1 2 3".

Hutch Over a year ago

in the sample.sh , second line can replace as tclsh sample.tcl "${my_array[@]}" "${my_arrayTWO[@]}" also works, thanks for this

moomster · Accepted Answer · 2022-09-05 13:15:13Z

Expanding on @glenn jackman's comment...

Expect treats an Array as a set of key-pair values, while Expect treats a List simply as a list.

Therefore to be able to pass an array/list as a single arg...

Array Example (myExpectArray.tcl)

array set myArray [lindex $argv 0];
foreach item [array name myArray] {
  puts $myArray($item)
}

Call the expect script from command line...

myExpectArray.tcl "0 dog 1 cat 2 rabbit"

To call this from bash, you'd need to loop through the array and build the string to pass to the expect script. Using a List is easier...

List Example (myExpectList.tcl)

set myList [lindex $argv 0];
for {set i 0} {$i < [llength $myList]} {incr i} {
  puts [lindex $myList $i]
}

Call the expect script from bash as follows...

myAnimals+=( "dog" "cat" "rabbit" )
myArgs=${myAnimals[@]}
myExpectList.tcl "$myArgs"

Note: You must convert the list ($myAnimals) to a string ($myArgs) otherwise Expect treats each element of the array as a unique arg.

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