bash concat strings in single variable using while read

Question

In the following script, I try to get all tables name from a mysql database and I expect all table's name printed out, but no matter what I do or which method I use, it just doesn't work. the printed string I suppose are tables name overlapped on each other:

watchdoglescabularyrchygsey

What's wrong with this script?

  mysql -Nse 'show tables' DATABASE |
    { 
    while read table
    do
    alltables="$alltables $table"
    done 
    echo $alltables;
    }

What is the output of the mysql command by itself? That said, always use IFS= read -r table unless you have a compelling reason not to. You might also want to check the output of echo "$alltables" | od to get a better idea of exactly what characters are in the value. — chepner
– chepner, Commented Mar 23, 2017 at 19:17
the output is tables name connected with \n\r, and that was the culprit. — primee
– primee, Commented Mar 24, 2017 at 8:27

Socowi · Accepted Answer · 2017-03-23 18:37:21Z

2

Could it be that mysql separates the table names by \n\r instead of \n? The read would then read First Table, \rSecond Table, and so on. In most linux terminals \r causes the cursor to jump back to the start of the current line. ABC\r_ will be printed as _BC.

Checking for `\r`

Execute mysql -Nse 'show tables' DATABASE | sed 's:\r:\\r:' and look at the output. The control character \r will be printed as the literal string \r.

Deleting the `\r`

Insert a ... | tr -d '\r' | ... between the commands.

answered Mar 23, 2017 at 18:37

Socowi

27.9k4 gold badges41 silver badges72 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

primee Over a year ago

the checking snippet didn't display \r, but it worked, thank you. :)

Collectives™ on Stack Overflow

bash concat strings in single variable using while read

1 Answer 1

Checking for `\r`

Deleting the `\r`

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Checking for \r

Deleting the \r

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related

Checking for `\r`

Deleting the `\r`