Bash Script Evaluate String Problems

Question

I'm trying to create a script to automatically delete all of the tables from a database using shell.

The commented out variable $drop works fine, however when I try to substitute in the table

for table in $tables
do
    command="'drop table ${table}'"

    # drop=$(${login} -e 'drop table test') -- this works fine
    drop=$(${login} -e $command)
    echo $drop
    # echo -e "Removed table ${table}"
done

turn on shell debugging to see what values are being used for $command, etc. add set -vx before your loop. to turn off, you can use set +vx. Good luck. — shellter
– shellter, Commented Aug 11, 2012 at 3:02
Hello, I used this and got these results:+ for table in '$tables' + set -vx + command=''\''drop table property_thumbnail'\''' + for table in '$tables' @shellter — JonMorehouse
– JonMorehouse, Commented Aug 11, 2012 at 3:10

glenn jackman · Accepted Answer · 2012-08-11 04:49:55Z

1

(major edit)

The issue is with your use of quotes. In your code, since you do not quote $command it is subject to word splitting by the shell. The $login command receives these arguments: "-e", "'drop", "table", "table_name'" -- note the stray single quotes in the second and last elements.

Do this:

command="drop table $table"
drop=$($login -e "$command")

edited Aug 11, 2012 at 4:49

answered Aug 11, 2012 at 3:13

glenn jackman

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3 Comments

JonMorehouse Over a year ago

Hmm, I tried this and am still having problems. I don't think drop should be an array, rather, it takes $table from the $tables array. When I use the syntax shown above, the command does not show at all?

JonMorehouse Over a year ago

Current Code: ` command="drop table ${table}" drop=("$login" -e "${command}") echo "${drop[@]}"` which prints out the correct commands, but doesn't actually run the command. When I try $("${drop[@]}") it shows error "no such directory"@glenn jackman

glenn jackman Over a year ago

@JonMorehouse, I misunderstood your question -- it is not clear what $login is. I have rewritten my answer.

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