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Char "^M" at end of each line in output file

Posted by Kan (Kan), 24 November 2005
I've prepared a expect script on a Linux box to telnet to a SUNOS box. In the telnet session, I ping to 2 remote host to check connectivity and output the ping result to a file.

However, when I use vi to view the file, there are strange char "^M" at the end of each line. How to prevent "^M" from writing into the output file?

Here is my script:
set timeout 300
set hostname IPAddress    
set username abc
set password pw
spawn telnet $hostname
expect "login: "
send "$username\r"
expect "Password:"
send "$password\r"
send "\r"
expect "bash$ "
set ret [open result.txt w]
send "ping\r"
send "ping\r"
send "uname\r"
expect "SunOS"
puts $ret "$expect_out(buffer)"
close $ret

Here is the result.txt view in vi:
bash$ ping^M is alive^M
bash$ ping^M is alive^M
bash$ uname^M

Posted by admin (Graham Ellis), 24 November 2005
At the end of each line you've got a carriage return - control M - character.   You'll see it in Tcl strings represented as \r.  Terminal output has a carriage return, line feed sequence on it as do Windows files - that's ^M^J or \r\n.  

The string trim command can be used to get rid of leading and trailing white space.

Posted by Kan (Kan), 25 November 2005
Thanks Graham.

It works after I string trim each line in $expect_out(buffer) before I write to the output file as follow:

set buf $expect_out(buffer)
foreach line [split $buf "\n"] {
   set line [string trim $line]
    puts $ret $line

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