Expect command when triggered by launchd


Login or Register for Dates, Times and to Reply

 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting Expect command when triggered by launchd
# 1  
Expect command when triggered by launchd

Hi folks,

Im having trouble with an expect command in a shell script I use to back up mac os x servers. This one is being run on a 10.8.2 Server as part of a larger bash script. The script executes perfectly all the way through when triggered on the command line, but when launchd triggers it at the scheduled time, the rest of the script executes fine, but the expect command doesnt send the password and so the slapconfig command doesn't complete, it just hangs there waiting.

Here is the relevant portion of my script:

Code:
/usr/bin/expect -c '
spawn /usr/sbin/slapconfig -backupdb "'"${recover}/_OD_Backup_${date}"'"
sleep 10
expect "'"Enter archive password:"'"
send "'"${passwd}\\r"'"
interact
' >/Users/admin/Desktop/slapconfig.log

Ive redirected stdout to a text file to see where it stops and this is what it outputs:

"spawn /usr/sbin/slapconfig -backupdb /Volumes/RAID/Administration/Backups/server.domain.com/20121116/_OD_Backup_20121116
2012-11-17 00:06:42 +0000 slapconfig -backupdb
Enter archive password:
"

Perhaps this is a problem with launchd running the script commands in a subshell or something along those line? I'm a bit stumped why the expect command completes when the script is triggered on the command line but not when scheduled with launchd.

Any help would be greatly appreciated!

Last edited by rowie718; 11-18-2012 at 07:53 PM..
# 2  
Often this sort of problem is caused by the lack of a controlling terminal. I am not a launchd user, but ssh has -t and -tt to force artficial controlling terminal generation. The -S sessiontype option looks promising.


What does your expect script exactly expect? Is the prompt the one expected?
# 3  
Figured it out!

It wasnt anything about launchd session types or anything else. After reading a bit of the book "Exploring Expect", I followed up on a hint they gave about adding another expect line so the expect command doesnt end as soon as the first match is made and responded to. Here is the code that works, which is in a larger bash script:

Code:
/usr/bin/expect -c '
spawn slapconfig -backupdb "'"${recover}/_OD_Backup_${date}"'"
sleep 10
expect "Enter archive password:"
send "'"${passwd}\r"'"
expect "============"
' >${logfile}

For context, and hopefully to help other folks backing up mac servers, here is the larger bash script (which is a modified/updated older script I found online). It has been tested on 10.8.2 and works whether triggered via command line or launchdaemon (must be run as root). Adjust parameters at top of the script. The two variables with brackets (< and >) are required:

Code:
#!/bin/bash

# Path to the root folder where the backups will be stored
# This path should not be on the root volume, and not accessible
# to non-administrators

recover_path="<path/to/backup/folder>"

# Log file location

logfile="/Library/Logs/Server_Backup.log"

# You can either backup all of the services (even those not in use)
# or you can specify which services you want to backup.

# Path to serveradmin command

serveradmincmd="/Applications/Server.app/Contents/ServerRoot/usr/sbin/serveradmin"

services=`$serveradmincmd list`
#services="afp ipfilter smb"

# This is the password you will use to recover your OD sparseimage.
# It should NOT be the same as your Directory Administrator password
# for security reasons.

passwd="<password>"

# Number of days worth of backups to keep

backupdays="30"

###############################################################
#### Advanced modification only. The rest can be left as is ###
###############################################################

# This is the hostname of the server the script is running on
# This variable is used so that the same script can be run
# from multiple servers on a single share point
server=`hostname`

# Purge backups older than the amount of days user has set above

find "${recover_path}/$server/"* -maxdepth 0 -mtime +$backupdays -print | xargs rm

# Get today's date and format it as YYYYMMDD
date=`date ''+%c%m%d'' | awk '{printf $5}'`

# Set the full path to where this days backups will be stored
recover=${recover_path}/$server/$date

mkdir -p "${recover}"
chmod 600 "${recover}"

# grab the server configuration plists
for service in $services; do
    $serveradmincmd settings $service > "${recover}/$service.txt"
    sleep 1
done

# Backup Open Directory

/usr/bin/expect -c '
spawn slapconfig -backupdb "'"${recover}/_OD_Backup_${date}"'"
sleep 10
expect "Enter archive password:"
send "'"${passwd}\r"'"
expect "============"
' >${logfile}

echo "Script Complete at `date`" >>${logfile}
exit 0

# 4  
So, your expectations were thrown off by quoting and escqping? Well, that's layering for you. Good luck!
# 5  
Quote:
Originally Posted by DGPickett
So, your expectations were thrown off by quoting and escqping? Well, that's layering for you. Good luck!
Not quite. I had been playing around with escaping and quoting and that wasn't the piece I was missing. The problem was that as soon as the first expect pattern was matched, and the appropriate response sent, the expect command exited, giving no time for the actual spawned process to run and complete. Adding another expect pattern that will not be matched means the expect command runs until it times out looking for that pattern. This approach gives us enough time for the spawned process (slapconfig) to conplete.

Not sure why it reacts differently based on launchd trigger, but this solution works.
Login or Register for Dates, Times and to Reply

Previous Thread | Next Thread
Thread Tools Search this Thread
Search this Thread:
Advanced Search

Test Your Knowledge in Computers #660
Difficulty: Medium
DOS uses a filesystem which supports 9.3 filenames: 9 characters for the filename and 3 characters for the extension.
True or False?

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Email need to be triggered

hi, Currently, in my code, the errors are written in log file. Additionally, i need to trigger the email of error captured. can we modify this script with email triggered along with existing command. echo "ERROR: $SCRIPT: $*" >>$LOGFILE (1 Reply)
Discussion started by: gowthamsoft
1 Replies

2. Shell Programming and Scripting

Scripts triggered via 'expect' - stderr lost

I have a bash script on server that runs fine when run interactively and writes stderr output to a file. However, when invoked through a 'expect' script run on Mac OS my laptop which does ssh to the server : generates the expected file, but file has no content. I suspect the stderr is getting... (1 Reply)
Discussion started by: sdudc
1 Replies

3. Shell Programming and Scripting

Capture output of command triggered in background

Is there any way to trigger a sequence of commands in parallel and capture their output in variables? e.g. something on the following lines x=`echo "X" &` y=`echo "Y" &` z=`echo "Z" &` so that $x, $y, and $z evaluate to X, Y and Z res. (7 Replies)
Discussion started by: jawsnnn
7 Replies

4. UNIX for Dummies Questions & Answers

Launchd-owned processes unexpected behavior

Ok, so I have been struggling with this for a few days and I think I need an explanation of a few things before I go any further. I'm not sure it's possible to do what I'm trying, so before I pull my hair out, here is what I'm doing: I have written a program in LiveCode that sits on our... (2 Replies)
Discussion started by: nextyoyoma
2 Replies

5. Shell Programming and Scripting

Expect command- need help

Hi All, I need help in making my script run perfectly as expected. This is a snippet from my script. I am trying to read the ";" from the below output using the expect command, but the command is not detecting it. Could you please help me correct the expect string? Snippet: ---- ---... (2 Replies)
Discussion started by: sonicj
2 Replies

6. Shell Programming and Scripting

Help with expect command

Hi, I am using following commands in my script to send a password to scp command. Everything is working fine except that I need a return code from the scp command. Do any one have an idea how to receive the exit code of scp command from expect. /usr/bin/expect << EOF spawn -noecho scp -pq... (0 Replies)
Discussion started by: pvamsikr
0 Replies

7. UNIX for Dummies Questions & Answers

Alert to be triggered

Hi, I need an alert to be triggered if any filesystem(imagine there are n no of filesystems) reaches more than 90%, it should send an alert to the mailbox stating which filesystem is at what percentage. How can I achieve this in unix? Many thanks. (8 Replies)
Discussion started by: venkatesht
8 Replies

8. OS X (Apple)

[launchd] Creating a basic firewall

Hi, I'm trying to use launchd to detect whether certain ports are opened and if they are then to take some appropriate action, e.g. close the port or, worst case scenario, down the whole net connection. Apparently, force closing a port is not possible without killing the offending binary so... (3 Replies)
Discussion started by: ASGR
3 Replies

9. OS X (Apple)

interval in a launchd script

Hi, i'm planning a to automate my backup with a rsync user deamon in my launchd and let that run every 2 hours. my server contains a lot of video data which can expand rapidly , up to 1TB, in an interval of 2 hours. now i'm wondering what will happen when a rsync is running longer then the... (1 Reply)
Discussion started by: wessel
1 Replies

10. Shell Programming and Scripting

Expect and auto expect command

I need to run a remote application(GUI) in a client.i.e on running a script in the client machine i should get the GUI application which is running in the server by providing password through the script.Will expect or autoexpect command suit for this scenario? could anyone help me by posting some... (0 Replies)
Discussion started by: arun_v
0 Replies

Featured Tech Videos