Filename expansion for expect script within bash

Question

I have the following bash script with an embedded expect script:

#!/bin/bash

if [ ! $# == 2 ]
  then
    echo "Usage: $0 os_base_version sn_version"
    exit
fi

if [ -e /some/file/path/$10AS_26x86_64_$2_*.bin ]
  then
    filename="/some/file/path/$10AS_26x86_64_$2_*.bin"
    echo ${filename}
else
  echo "install archive does not exist."
  exit
fi

{
  /usr/bin/expect << EOD
  set timeout 20
  spawn "${filename}"

  expect {
      "Press Enter to view the End User License Agreement" {
          send "\r"
          exp_continue
      }
      "More" {
          send " "
          exp_continue
      }
      "Do you accept the End User License Agreement?" {
          send "y\r"
      }
  }
  interact
  expect eof
EOD
}

In the folder are several files in the format {x}0AS_26x86_64_{x.x.x}_{rev}.bin

When I run the script, I get the correct filename on the first echo. But when I try to pass this to the expect script using ${filename}, the filename expansion is gone.

Sample output:

# ./make.sh 2 1.2.3
/some/file/path/20AS_26x86_64_1.2.3_45678.bin
spawn /some/file/path/20AS_26x86_64_1.2.3_*.bin
couldn't execute "/some/file/path/20AS_26x86_64_1.2.3_*.bin": no such file or directory
    while executing
"spawn /some/file/path/20AS_26x86_64_1.2.3_*.bin"

As you can see the $filename shows correct with the echo, but not inside the expect part.

Edit:

Just run the script with -x, and it looks like the filename variable never get the full filename expansion, only the echo does.

# ./make.sh 2 1.2.3
+ '[' '!' 2 == 2 ']'
+ '[' -e /some/file/path/20AS_26x86_64_1.2.3_45678.bin ']'
+ filename='/some/file/path/20AS_26x86_64_1.2.3_*.bin'
+ echo /some/file/path/20AS_26x86_64_1.2.3_45678.bin
/some/file/path/20AS_26x86_64_1.2.3_45678.bin
+ exit

Answer 1

You are never actually assigning a specific filename to the variable. What you are doing is setting the variable to a glob pattern. Then, when you pass the variable to echo, the glob pattern is expanded, so you see your file's name pritned. However, the variable has never been set to a specific file name.

So, you need a better way of getting the file name. Something like:

#!/bin/bash

## Make globs that don't match anything expand to a null
## string instead of the glob itself
shopt -s nullglob
## Save the list of files in an array
files=( /some/file/path/$10AS_26x86_64_$2_*.bin )
## If the array is empty
if [ -z $files ]
then
    echo "install archive does not exist."
    exit
## If at least one file was found    
else
    ## Take the first file 
    filename="${files[0]}"
    echo "$filename"
fi

{
  /usr/bin/expect << EOD
  set timeout 20
  spawn "${filename}"

  expect {
      "Press Enter to view the End User License Agreement" {
          send "\r"
          exp_continue
      }
      "More" {
          send " "
          exp_continue
      }
      "Do you accept the End User License Agreement?" {
          send "y\r"
      }
  }
  interact
  expect eof
EOD
}