How can I remove special characteres from expect? - bash

Question

So I'm using the next expect script in order to get the running-config of a switch and then save it to a file:
#!/usr/bin/expect
set timeout 9
set username [lindex "foo"]
set password [lindex "bar"]
set hostname [lindex "1.2.3.4"]
spawn ssh -q $username#$hostname
expect {
timeout { send_user "\nTimeout!\n"; exit 1 }
"*assword"
}
send "$password\n"
expect {
timeout { send_user "\nWrong password\n" ; exit 1 }
"switch-00>"
}
send "enable\n"
expect {
"switch-00#"
}
send "show running-config\n"
log_file -noappend log.txt
expect {
-ex "--More--" { send -- " "; exp_continue }
"*#" { log_file; send "exit\r" }
}
send "exit\n"
close
It works as it should except for this:
--More--^H ^H^H ^H^H ^H^H ^H^H ^H^H ^H^H ^H^H ^H
which is appearing in log.txt every time "--More--" gets printed.
It's not an issue to remove "--More--" later on using bash but if I do:
grep "^H" log.txt
there's no output, so I cannot remove it as it doesn't match.
I was trying to find a way to not output special characteres with expect if possible but didn't find any, so I'm asking here in case anyone knows.
A solution using bash would help me aswell but using expect is prefered.

Answer 1

You could use the bash tr utility. From the man page
NAME
tr -- translate characters
DESCRIPTION
The tr utility copies the standard input to the standard output with sub-
situation or deletion of selected characters.
SYNOPSIS
tr [-Ccsu] string1 string2
tr [-Ccu] -d string1
-C Complement the set of characters in string1, that is ``-C ab''
includes every character except for `a' and `b'.
-c Same as -C but complement the set of values in string1.
-d Delete characters in string1 from the input.
To Strip out non-printable characters from file1.
tr -cd "[:print:]\n" < file1 # This is all you need.