WebTech Varna 2007

1. WebTech Varna 2007
Expect – the unexpected
Marian Marinov – mm@yuhu.biz
System Architect - Siteground.com

2. Agenda
➢ What is Expect and where it can help
➢ Implementations
`
➢ UNIX tool expect
➢ Python pexpect
➢ Perl Expect
➢ PHP expect
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Marian Marinov - mm@yuhu.biz 1/30 WebTech Varna 2007

3. What is Expect
➢ Automating Interactive Applications
➢ Unique System Administrators tool
➢ Just Another TCL extension
➢ Great automated application tester
Where to use it:
➢ passwd automations
➢ automation of ncurses based application
➢ automated patch management
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Marian Marinov - mm@yuhu.biz 2/30 WebTech Varna 2007

4. UNIX Expect application
Requirements: tcl & expect
Don Libes - http://expect.nist.gov/
hackman@gamelon:~$ expect
expect1.1> send "hello world"
hello worldexpect1.2> exit
hackman@gamelon:~$ expect
expect1.1> send "hello worldn";
hello world
expect1.2> exit
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Marian Marinov - mm@yuhu.biz 3/30 WebTech Varna 2007

5. UNIX Expect application
hackman@gamelon:~$ cat speak.exp
#!./expect -f
send "hello worldn"
hackman@gamelon:~$ ./speak.exp
hello world
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Marian Marinov - mm@yuhu.biz 4/30 WebTech Varna 2007

6. UNIX Expect application
send – sending string to the command
send_user – sending string to STDOUT
send_log – sending string to text log file
set timeout -1|0|60 – maximum wait for
command input
stty -echo – turn off KBD echo
spawn – start a program
interact – returns the control of the
started command back to user
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Marian Marinov - mm@yuhu.biz 5/30 WebTech Varna 2007

7. UNIX Expect application
match_max 100000 - max buffer size
log_user 0|1 – enable/disable logging to
STDOUT
log_file filename – file where to store the
script output as addition to STDOUT
expect -exact – match exact string
expect -re – match regular expression
expect eof – wait the command to finish
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Marian Marinov - mm@yuhu.biz 6/30 WebTech Varna 2007

8. UNIX Expect application
expect {
# nestead expectes
-re "" {
}
-exact "" {
}
-re "" {
}
}
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Marian Marinov - mm@yuhu.biz 7/30 WebTech Varna 2007

9. UNIX Expect application
Get some user input:
stty -echo
expect_user -re "(.*)n"
set password $expect_out(1,string)
send_user "n"
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Marian Marinov - mm@yuhu.biz 8/30 WebTech Varna 2007

10. UNIX Expect application
Show some examples :)
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Marian Marinov - mm@yuhu.biz 9/30 WebTech Varna 2007

11. UNIX Expect application
I'm stupid and
I didn't understood anything
Can I still use Expect?
YES
autoexpect
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Marian Marinov - mm@yuhu.biz 10/30 WebTech Varna 2007

12. UNIX Expect application
autoexpect ftp ftp.example.com
autoexpect -f ftp.exp ftp ftp.example.com
-c – conservative mode
-p – prompt mode
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Marian Marinov - mm@yuhu.biz 11/30 WebTech Varna 2007

13. Python pexpect package
URL: http://pexpect.sourceforge.net/
Requirements: python2.4 & pty package
Installation:
1. download pexpect-2.1.tar.gz
2. tar zxf pexpect-2.1.tar.gz
3. cd pexpect-2.1
4. python setup.py install
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Marian Marinov - mm@yuhu.biz 12/30 WebTech Varna 2007

14. Python pexpect package
import pexpect
child = pexpect.spawn ('ftp ftp.openbsd.org')
child.expect ('Name .*: ')
child.sendline ('anonymous')
child.expect ('Password:')
child.sendline ('test@example.com')
child.expect ('ftp> ')
child.sendline ('cd pub')
child.expect('ftp> ')
child.sendline ('get ls-lR.gz')
child.expect('ftp> ')
child.sendline ('bye')
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Marian Marinov - mm@yuhu.biz 13/30 WebTech Varna 2007

15. Python pexpect package
Regular expression problems:
matching the end of the line can be tricky :)
The $ pattern for end of line match is useless.
child.expect ('w+rn') - matching word at the end
of the line
minimal match(instead of the standard greedy):
child.expect ('.+') - match always one char
child.expect ('.*') - match always zero or one char
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Marian Marinov - mm@yuhu.biz 14/30 WebTech Varna 2007

16. Expect for Perl
Packages:
Expect
Expect::Simple
Installation:
perl -MCPAN -e 'install Expect'
perl -MCPAN -e 'install Expect::Simple'
Download and compile
(http://search.cpan.org)
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Marian Marinov - mm@yuhu.biz 15/30 WebTech Varna 2007

17. Expect for Perl
Expect->new();
$object->spawn(@command);
$object->debug($debug_level);
$object->exp_internal(0 | 1);
$object->raw_pty(0 | 1);
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Marian Marinov - mm@yuhu.biz 16/30 WebTech Varna 2007

18. Expect for Perl
$object->match();
$object->matchlist();
$object->match_number();
$object->error();
$object->command();
$object->exitstatus();
$object->do_soft_close();
$object->restart_timeout_upon_receive(0 | 1);
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Marian Marinov - mm@yuhu.biz 17/30 WebTech Varna 2007

19. Expect for Perl
$object->log_group(0 | 1 | undef);
$object->log_user(0 | 1 | undef);
$object->log_file("filename" | $filehandle | &coderef |
undef);
$object->match_max($max_buffersize or undef);
$object->pid();
$object->send_slow($string_to_send);
$object->send_slow($delay, @strings_to_send);
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Marian Marinov - mm@yuhu.biz 18/30 WebTech Varna 2007

20. Expect in PHP
Requirements:
libexpect >= 5.43.0
PHP >= 4.3.0
PECL
Installation:
pear install expect
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Marian Marinov - mm@yuhu.biz 19/30 WebTech Varna 2007

21. Expect in PHP
ini_set ("expect.loguser", "Off");
$stream = fopen ("expect://ssh root@remotehost
uptime", "r");
$cases = array (
array (0 => "password:", 1 => PASSWORD)
);
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Marian Marinov - mm@yuhu.biz 20/30 WebTech Varna 2007

22. Expect in PHP
switch (expect_expectl ($stream, $cases)) {
case PASSWORD:
fwrite ($stream, "passwordn");
break;
default:
die ("Error was occurred while connecting to the
remote host!n");
}
while ($line = fgets ($stream)) {
print $line;
}
fclose ($stream);
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Marian Marinov - mm@yuhu.biz 21/30 WebTech Varna 2007