I've a script which works fine on FC20. But, when I try to execute the same script on CentOS(CentOS Linux release 7.5.1804 (Core)), it hangs. On further, investigation it was revealed that, it is not able to match the prompt given. Please note it is able to match host prompt but not application prompt. Here is a brief detail of the issue
Code of the wrapper function which is used to create object of Net::Telnet-
package api::Telnet; use strict; use warnings; use Net::Telnet; use Exporter; use Carp; our @ISA = qw (Exporter); our @EXPORT = qw ( &open_pty &close_pty ); # Constant global variables use constant SSH_TIMEOUT => 1800; sub spwan_pty { my (@cmd) = @_; my ($pid, $tty, $tty_fd); # Create a new pseudo terminal use IO::Pty (); my $pty = new IO::Pty or die $!; # Execute the program in another process # Child process unless ($pid = fork) { die "problem spawning program: $!\n" unless defined $pid; # Disassociate process from existing controlling terminal use POSIX (); POSIX::setsid or die "setsid failed: $!"; # Associate process with new controlling terminal $pty->make_slave_controlling_terminal; $pty->set_raw(); $tty = $pty->slave(); $tty_fd = $tty->fileno; close $pty; # Make stdio use the new controlling terminal open STDIN, "<&$tty_fd" or die $!; open STDOUT, ">&$tty_fd" or die $!; open STDERR, ">&STDOUT" or die $!; close $tty; exec @cmd or die "problem executing $cmd[0]\n"; } # end child process $pty; } sub open_pty { my (%args) = @_; # Start ssh program. my $pty = &spwan_pty("ssh", "-l", $args{user_name}, "-e", "none", "-F", "/dev/null", "-o", "PreferredAuthentications=password", "-o", "NumberOfPasswordPrompts=1", "-o", "StrictHostKeyChecking=no", "-o", "UserKnownHostsFile=/dev/null", $args{ip_addr} ); # Create a Net::Telnet object to perform I/0 on ssh's tty my $ssh = new Net::Telnet ( -fhopen => $pty, -prompt => $args{prompt}, -telnetmode => 0, -cmd_remove_mode => 1, -timeout => SSH_TIMEOUT, -output_record_separator => "\r", #-errmode => sub { print "Telnet FAIL\n"; } ); # Wait for the password prompt and send password. $ssh->waitfor(-match => '/password: ?$/i', -errmode => "return") or die "problem connecting to \"$args{ip_addr}\": ", $ssh->las +tline; $ssh->print($args{user_pswd}); # Wait for the shell prompt. my (undef, $match) = $ssh->waitfor( -match => $ssh->prompt, -match => '/^Permission denied/m', -errmode => "return" ) or return $ssh->error("login failed: expected shell prompt ", "d +oesn't match actual\n"); return $ssh->error("login failed: bad login-name or password\n") i +f $match =~ /^Permission denied/m; # logging $ssh->input_log($args{log_file}); $ssh->cmd("ifconfig"); $ssh->cmd("date"); return $ssh; } sub close_pty { my ($tty) = shift; $tty->close(); } 1;
Once Net:Telnet object is obtained, it is used to spawn an interactive application. Here is the code snippet of the same-
my $host_prompt = '/[\$%#>] $/'; my $util_prompt = '/(\s)*Command: (\s)*/i'; my $owner = &open_pty ( user_name => "<user_name>", user_pswd => "<password>", ip_addr => "127.0.0.1", prompt => $host_prompt, log_file => 'Log/Owner' ); $owner->cmd ( String => "cd <navigate to application path>", Prompt => + $host_prompt ); $owner->cmd ( String => "<Launch the application>", Prompt => $util_pr +ompt ); $owner->cmd ( String => "<Execute command>", Prompt => $util_prompt );
The code successfully creates a Net::Telnet object and spawn the application, but it is unable to match the prompt of the application, due to which it hungs and the script is unable to proceed forward. Here is the log generated-
em1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet xxx.xxx.xxx.xxx netmask 255.255.252.0 broadcast xxx.xxx +.xxx.xxx inet6 xxxx::xxxx:xxxx:xxxx:xxxx prefixlen 64 scopeid 0x20<li +nk> ether xx:xx:xx:xx:xx:xx txqueuelen 1000 (Ethernet) RX packets 393842 bytes 40650026 (38.7 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 138388 bytes 15595013 (14.8 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 device interrupt 16 memory 0x92f00000-92f20000 lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10<host> loop txqueuelen 1000 (Local Loopback) RX packets 5296 bytes 928222 (906.4 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 5296 bytes 928222 (906.4 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 inet xxx.xxx.xxx.xxx netmask xxx.xxx.xxx.xxx broadcast xxx.x +xx.xxx.xxx ether xx:xx:xx:xx:xx:xx txqueuelen 1000 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 [root@hyd1658 ~]# Wed Jan 16 15:29:54 IST 2019 . . . . Command:
Please Note: The same code works on FC20, but fails on CentOS
Could anyone please pinpoint the issue or suggest a remedy for the same
In reply to Unable to match Net::Telnet Prompt on CentOS. However, the same prompt works fine on FC20 by shoundic
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