strange echo output

Question

Can anybody explain this behaviour of the bash shell which is driving me nuts

[root@ns1 bin]# export test=`whois -h whois.lacnic.net 187.14.6.108 | grep -i inetn         


        

Answer 1

This is almost certainly a carriage return. echo is doing its job correctly and emitting the string to your terminal; the problem is that your terminal is treating a part of the string as a command for it to follow (specifically, a LF character, $'\r', telling it to send the cursor to the beginning of the existing line).

If you want to see the contents of $test in a way which doesn't allow your terminal to interpret escape sequences or other control characters, run the following (note that the %q format string is a bash extension, not available in pure-POSIX systems):

printf '%q\n' "$test"

This will show you the precise contents formatted and escaped for use by the shell, which will be illuminative as to why they are problematic.

To remove $'\r', which is almost certainly the character giving you trouble, you can run the following parameter expansion:

test=${test//$'\r'/}

Unlike solutions requiring piping launching an extra process (such as tr), this happens inside the already-running bash shell, and is thus more efficient.