for some time I am struggling to get the exit code of a script which I am running from within expect.
It is a BASH script and the questionable part looks like this:
expect -c "
log_file $LOG
spawn su - $ora_user
expect ""
send \"source $oraenv_binary\r\"
expect \"ORACLE_SID = \[$ora_user\] \?\"
send \"$SID\r\"
expect \"The Oracle base has been set to /oracle/$SID\"
send \"$execPATHroot/$subscript $args_subscript\r\"
expect ""
send \"echo \$?\r\"
expect -re \"(\\d+)\" {
set result \$expect_out(1,string)
}
send_user \"subscript exit code: \$result\"
log_file
send \"exit\r\"
expect ""
exit [lindex \$result 3]"
sub_rc=$?
Needed to say that this is one of many tries to get the code, however, unsuccessfully. I guess that my problem lies in incorrectly escaped characters or wrong use of brackets.....
When debugging, I am getting the following:
[336] oraenv_binary=/usr/local/bin/oraenv
[338] expect -c '
log_file /var/opt/osit/oracle/log/ora_sbp_patching_root.bash.log
spawn su - oracle
expect
send "source /usr/local/bin/oraenv\r"
expect "ORACLE_SID = \[oracle\] \?"
send "H95\r"
expect "The Oracle base has been set to /oracle/H95"
send "/opt/osit/oracle/bin/ora_sbp_patching_orausr.bash -s H95 -a CHECK -p /imports/e2r2s48ifde0002/CDSAP/DB/oracle/ORA19/SBP/SBP_1915_220419_202205 -h /imports/e2r2s48ifde0002/CDSAP/DB/oracle/ORA19/SBP/SBP_1915_220419_202205/README19P_2205-70004508.HTM -u oracle\r"
expect
send "echo $?\r"
expect -re "(\d+)" {
set result $expect_out(1,string)
}
send_user "subscript exit code: $result"
log_file
send "exit\r"
expect
exit [lindex $result 3]'
.....subscript runs here OK with exit code 0 in this case
-sh-4.2$ subscript exit code: decho $?
0
-sh-4.2$ exit
logout
expected integer but got ""
while executing
"exit [lindex $result 3]"
[357] sub_rc=0
It seems to me that the regex part "(\d+)" is not OK, but perhaps, it is completely a mess... :-)
Please help.
I have read and tried these recommendations:
Is there a way to expect output without removing it from the buffer in Tcl expect?
https://wiki.tcl-lang.org/page/How+Expect+can+capture+the+exit+code+from+a+remote+command
https://www.unix.com/shell-programming-and-scripting/144812-expect-script-obtain-exit-code-remote-command.html
You have this
expect -re "(\d+)" {
set result $expect_out(1,string)
}
send_user "subscript exit code: $result"
and we can see the output is
-sh-4.2$ subscript exit code: decho $?
0
Because the regular expression "(\d+)" is in double quotes, backslash substitutions will occur, and the pattern becomes (d+) which may not match (do you get a 10 second delay at that point?) -- I suspect this is why $result is empty.
Backslashes are prevalent in regular expressions. Using braces to quote them is the way to go:
expect -re {\d+} {set result $expect_out(0,string)}
Running your expect code with expect -d (or set exp_internal 1 in the code) emits very verbose expect debug output that is extremely useful to see how your patterns are matching (or not).
Using quoted shell heredocs is (IMO) preferable to using quoted strings to encapsulate code.
Consider
expect -c "
send_user \"my home is \$env(HOME)\\n\"
"
versus
expect << 'END_CODE'
send_user "my home is $env(HOME)\n"
END_CODE
With this technique, you pass shell variable to expect through the environment:
export ora_user=oracle
expect << 'END_EXPECT'
#...
spawn su - $env(ora_user)
END_EXPECT
thanks a lot for your answer Glenn, interesting points mentioned.
Regarding the braces versus double quotes - I have changed it like that, but no effect. I have those double quotes escaped by backslash within my code - I think the effect is the same, however, definitely it looks nicer to me and evidently it is safer.
I have played with the debug mode of expect - thanks for that, I can see much more info.
I have noticed that expect holds much more stuff than I "expected" :-)
==> this is just a snippet:
.\r\n-sh-4.2$ " (spawn_id exp7) match regular expression "\d+"? (No Gate, RE only) gate=yes re=yes
expect: set expect_out(0,string) "4"
expect: set expect_out(spawn_id) "exp7"
expect: set expect_out(buffer) "\r\n-sh-4"
can't read "expect_out(1,string)": no such element in array
while executing
"set result $expect_out(1,string)"
invoked from within
"expect -re {\d+} {set result $expect_out(1,string)}"
As you can see, when I am sending the subscript to be executed I am expecting "" i.e. nothing, just the new prompt line.
However, at that point expect is full of stuff, not at all blank - I think, I need to define the prompt exactly:
-sh-4.2$
and then I need to expect it, together with echoed exit code $? and somehow separate exit code integer to get what I want...... I will keep trying.
The final code which works is as follows (much of the credit goes to Glenn for his numerous advices) :
expect -c "
log_file $LOG
spawn su - $ora_user
expect -re {\$ $}
send \"PS1='>'\r\"
expect -re {>$}
send \"source $oraenv_binary\r\"
expect {ORACLE_SID = \[$ora_user\] ? }
send \"$SID\r\"
expect \"The Oracle base has been set to /oracle/$SID\"
send \"$execPATHroot/$subscript $args_subscript\r\"
expect { (subscript) ; exp_continue }
expect -re {>$}
send \"echo \$?\r\"
expect -re {(\d+)\r\n>$} {set result \$expect_out(1,string)}
send_user \"subscript exit code:\$result\n\"
log_file
send \"exit\r\"
expect \"logout\"
exit [lindex \$result 0]"
sub_rc=$?
echo sub_rc:$sub_rc
The first thing after spawn su - $ora_user is to set the prompt by send \"PS1='>'\r\" in order to make new lines with prompt less intrusive to expect.
Then after send \"$execPATHroot/$subscript $args_subscript\r\" I have used the fact, that I have written the subscript to have every line of output populated by (subscript) keyword. So while the subscript produces the output, the expect keeps going by exp_continue.
When the $subscript ends, the prompt > appears into which the expect sends echo $? to get exit code of the $subscript.
This appears on the screen as:
>echo $?
0
>
so the code should expect the integer, return and the new line with prompt - i.e. {(\d+)\r\n>$}. At that time the expect matches the output and expect_out(1,string) is correctly populated:
send: sending "echo $?\r" to { exp7 }
Gate keeper glob pattern for '(\d+)\r\n>$' is '*
>'. Activating booster.
expect: does "" (spawn_id exp7) match regular expression "(\d+)\r\n>$"? Gate "*\r\n>"? gate=no
echo $?
0
>
expect: does "echo $?\r\n0\r\n>" (spawn_id exp7) match regular expression "(\d+)\r\n>$"? Gate "*\r\n>"? gate=yes re=yes
expect: set expect_out(0,string) "0\r\n>"
expect: set expect_out(1,string) "0"
expect: set expect_out(spawn_id) "exp7"
expect: set expect_out(buffer) "echo $?\r\n0\r\n>"
Another thing to mention is \n within send_user \"subscript exit code:\$result\n\" so to have new line next..
The last change to the code in question is:
exit [lindex \$result 0]"
I have changed the index to 0 as variable result has just one item and index 0 stands for 1st item in the list.
I'm trying to write a shell function that spawns a ssh process and authentificates with a password. Then, I'd like to use the spawned process to do further stuff with expect.
Here's the function I have so far:
ssh_cmd() {
ssh $USER#$HOST 2>&1 | expect -c "
log_user 0
set timeout 5
expect password: {
send \"$PASS\n\"
sleep 2
log_user 1
}
"
}
And then I'd like to use given function in other places to interact with the ssh process like this:
ssh_cmd | expect -c "
expect '#' {
send pwd\n
send exit\n
}
expect eof
"
However, running the ssh_cmd function with -d option for expect I get the following result:
expect version 5.45.4
expect: does "" (spawn_id exp0) match glob pattern "password:"? no
ubnt#ui1's password: expect: timed out
From what I understand, the output of ssh does not get piped correctly. I know the common way to do this would be to use spawn, but that would mean the process would get killed after expect exits and I could not have a generic function that authentificates ssh sessions and keeps the process alive for further usage.
What you're designing won't work. Expect needs the process to be spawned from within the expect interpreter using the spawn command. Passing the command's stdout into expect is insufficient.
You could try this:
ssh_cmd() {
# a default bit of code if user does not provide one.
# you probably want some checking and emit an error message.
local user_code=${1:-set timeout 1; send "exit\r"; expect eof}
expect -c "
log_user 0
set timeout 5
spawn ssh -l $USER $HOST
expect password: {
send \"$PASS\n\"
sleep 2
log_user 1
}
$user_code
"
}
and then invoke it like:
ssh_cmd '
expect "#" {
send pwd\r
send exit\r
}
expect eof
'
Note that single quotes have no special meaning in expect, they are just plain characters: you probably don't want to expect the prompt to be the 3 character pattern '#'
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 "$password\n"
expect {
timeout { send_user "\nWrong password\n" ; exit 1 }
"switch-00>"
}
send "enable\n"
expect {
"switch-00#"
}
send "show running-config\n"
log_file -noappend log.txt
expect {
-ex "--More--" { send -- " "; exp_continue }
"*#" { log_file; send "exit\r" }
}
send "exit\n"
close
It works as it should except for this:
--More--^H ^H^H ^H^H ^H^H ^H^H ^H^H ^H^H ^H^H ^H
which is appearing in log.txt every time "--More--" gets printed.
It's not an issue to remove "--More--" later on using bash but if I do:
grep "^H" log.txt
there's no output, so I cannot remove it as it doesn't match.
I was trying to find a way to not output special characteres with expect if possible but didn't find any, so I'm asking here in case anyone knows.
A solution using bash would help me aswell but using expect is prefered.
You could use the bash tr utility. From the man page
NAME
tr -- translate characters
DESCRIPTION
The tr utility copies the standard input to the standard output with sub-
situation or deletion of selected characters.
SYNOPSIS
tr [-Ccsu] string1 string2
tr [-Ccu] -d string1
-C Complement the set of characters in string1, that is ``-C ab''
includes every character except for `a' and `b'.
-c Same as -C but complement the set of values in string1.
-d Delete characters in string1 from the input.
To Strip out non-printable characters from file1.
tr -cd "[:print:]\n" < file1 # This is all you need.
#!/bin/bash
/usr/bin/expect << SSHLOGIN
spawn ssh -o StrictHostKeyChecking=no admin#$host
expect {
Password: {
send "Pass$word\n"
expect {
OK: {
send "xstatus\n"
send "quit\n"
}
}
}
}
SSHLOGIN
It is not able to ssh because it is not escaping the '$' character in "Pass$word\n" since $ is part of the password and there is no variable being passed. How would you escape it? I know in bash, you would add '\', but since the password is in the expect script portion, that does not work.
EDIT:
changing Pass$word\n to Pass\\\$word\n works
Here-documents are bash code, so you'd still use \$.
The expect script is TCL, so you'll need to escape the $ there too. With two levels of escaping, you get:
send "Pass\\\$word\n"
I have a variable in bash return from a function call getpassword() which return "apple$123123"
FOO=`getpassword`
I would like to use FOO variable which contains $ inside and pass into expect program
expect -c "\
set timeout 90
set env(TERM)
spawn rdesktop 192.168.11.1
expect \"Password:\"
send -- \"'${FOO}\n'\"
interact
"
}
There is an error coming out as $FOO contain dollar-sign
Password: can't read "123": no such variable
while executing
How can i solve this kind of problem? The way i think is that to pack escape character into FOO, using sed?
Thanks
You could try this:
# below is purposely on one line -- it sets the FOO env var
# only for the duration of the expect command.
FOO=$(getpassword) expect -c '
set timeout 90
set env(TERM) {are you missing something here?}
spawn rdesktop 192.168.11.1
expect "Password:"
send -- "$env(FOO)\r" # you send '\r' not '\n'
interact
'
Using single quotes make it easier to write (and read) the expect script (without all the backslashes). Testing:
$ getpassword() { echo 'abc$123'; }
$ FOO=$(getpassword) expect -c 'puts "pw=$env(FOO)"'
pw=abc$123
$ echo "> $FOO <"
> <