Brace expansion problem in Bash

mglenney · #1 (**permalink**) 07-02-2009

I have a script that takes an option for server pools to run the script against. The option is given as a comma separated list (ie, -p 201,204,301).

I'm using eval and brace expansion to get those pool numbers into an array. It works fine unless only 1 pool number is given. Here's the code:

Code:

while [ "$1" != "" ]; do
  case $1 in
    -p  )               shift
                        pools=($(for i in $(eval echo {$1}); do echo $i; done | sort))
                        ;;

If multiple pools given:

Code:

[me@server bin]$ ./project_nunenhoffen.sh -p 201,202
+ '[' -p '!=' '' ']'
+ case $1 in
+ shift
+ pools=($(for i in $(eval echo {$1}); do echo $i; done | sort))
++ sort
+++ eval echo '{201,202}'
++++ echo 201 202
++ for i in '$(eval echo {$1})'
++ echo 201
++ for i in '$(eval echo {$1})'
++ echo 202
+ shift
+ '[' '' '!=' '' ']'

If single pool given:

Code:

[me@server bin]$ ./project_nunenhoffen.sh -p 201
+ '[' -p '!=' '' ']'
+ case $1 in
+ shift
+ pools=($(for i in $(eval echo {$1}); do echo $i; done | sort))
++ sort
+++ eval echo '{201}'
++++ echo '{201}'
++ for i in '$(eval echo {$1})'
++ echo '{201}'
+ shift
+ '[' '' '!=' '' ']'

So if a single pool is given it leaves the braces around it which is bad. I could do a test of $1 to see if there are any commas and process it different if there aren't but I was wondering if there's a better solution than that. Also wondering if how I handled getting the pool numbers into an array was the best way to do it (eval & brace expansion).

Thanks,

Mike G.

vgersh99 · #2 (**permalink**) 07-02-2009

Code:

#!/bin/ksh

list='201,204,301'

IFS=,; set -A array ${list}

typeset -i i=0
while (( $i < ${#array[*]} ))
do
  echo "${array[$i]}"
  ((i=i+1))
done;

mglenney · #3 (**permalink**) 07-02-2009

Quote:

Originally Posted by vgersh99

Code:

#!/bin/ksh

list='201,204,301'

IFS=,; set -A array ${list}

typeset -i i=0
while (( $i < ${#array[*]} ))
do
  echo "${array[$i]}"
  ((i=i+1))
done;

I'm using Bash which doesn't have -A option for set and, from what I can tell, doesn't have an equivalent. I wish it did because you basically do what I need in a single line with your example.

For now I've solved my problem this way:

Code:

while [ "$1" != "" ]; do
  case $1 in
    -p  )               shift
                        case $1 in
                          *,* ) pools=( $(for i in $(eval echo {$1}); do echo $i; done | sort) ) ;;
                          *   ) pools=$1 ;;
                        esac
                        ;;

vgersh99 · #4 (**permalink**) 07-02-2009

Code:

#!/bin/bash

list='201,204,301'

IFS=,; array=(${list})

typeset -i i=0
while (( $i < ${#array[*]} ))
do
  echo "${array[$i]}"
  ((i=i+1))
done;

mglenney · #5 (**permalink**) 07-02-2009

Perfect. I was so hung up on solving it using brace expansion.

Thank you!!

cfajohnson · #6 (**permalink**) 07-03-2009

Quote:

Originally Posted by vgersh99

Code:

#!/bin/bash

list='201,204,301'

IFS=,; array=(${list})

typeset -i i=0
while (( $i < ${#array[*]} ))
do
  echo "${array[$i]}"
  ((i=i+1))
done;

All of the above is equivalent to:
Code:
list='201,204,301'
array=( ${list//,/ } )
printf "%s\n" "${array[@]}"

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