Working with bash arrays inside an expect script

Question

So I currently have a bash script using expect that needs to send an array of commands into a console. As can be seen below I use IFS to divide these on the newline and I then put them into a variable cmds_eval with the expect script. My hope was then to use $cmds_eval as seen below to send a bunch of commands into the expect script all at once. This doesn't work. It seems $cmds_eval is not being interpreted the way I was thinking it might. What would be the appropriate way to do this? I don't believe there is anyway to do the foreach inside the expect script but if there is... The script below has been simplified of course...

  cmds_eval=""                                                                  

  OLDIFS=$IFS                                                                   
  IFS="\n" read -ra CMDS <<< "$cmds"                                            
  for c in "${CMDS[@]}"; do                                                     
    cmds_eval+="send -- \"$c\\r\"\r\n"                                          
    cmds_eval+="expect \"*myprompt*\"\n"                                   
  done                                                                          
  IFS=$OLDIFS                                                                   

  expect <<- DONE                                                               
    spawn my ssh session                                                     
    expect "*foobar:*"                                                        
    send -- "foobar\r"                                                          
    expect "*foobar:*"                                                        

    $cmds_eval                                                                  

    send -- "foobar\r" 
DONE

cmds looks something like this:

cmds="pwd
mv myfile ..
ls"

Can you show the earlier parts of the script and the value of $cmds? — konsolebox
– konsolebox, Commented Sep 22, 2013 at 4:09
I've added an example of what cmds looks like... It in fact goes through a lot more than just that but that should be good enough... — David Mokon Bond
– David Mokon Bond, Commented Sep 22, 2013 at 4:12

konsolebox · Accepted Answer · 2013-09-22 04:17:11Z

2

I think your IFS does not set itself to a true newline:

IFS="\n" read -ra CMDS <<< "$cmds"

should be

IFS=$'\n' read -ra CMDS <<< "$cmds"

Also perhaps prefer readarray if possible:

readarray -t CMDS <<< "$cmds"
for c in "${CMDS[@]}"; do
  cmds_eval+="send -- \"$c\\r\"\r\n"
  cmds_eval+="expect \"*myprompt*\"\n"
done

Instead of

OLDIFS=$IFS
IFS="\n" read -ra CMDS <<< "$cmds"
for c in "${CMDS[@]}"; do
  cmds_eval+="send -- \"$c\\r\"\r\n"
  cmds_eval+="expect \"*myprompt*\"\n"
done
IFS=$OLDIFS

Also if you want to separate your lines with newlines, don't use "\n". Instead use $'\n':

  cmds_eval+="send -- \"$c\\r\"$'\n'
  cmds_eval+="expect \"*myprompt*\"$'\n'

edited Sep 22, 2013 at 4:17

answered Sep 22, 2013 at 4:11

konsolebox

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1 Comment

David Mokon Bond Over a year ago

thanks, works. Note to other people doing this. Ensure if you pass cmds from elsewhere you do "$cmds" otherwise the spaces make $cmds into part of the arg vector.

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