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I want to write a script which executes the following commands:

./virtuoso-t -f -c /home/var/lib/virtuoso/db/virtuoso.ini

which gives the following output -- after "Server online at 1111" appears on screen I want to issue another command ./isql 1111 dba dba. I dont want to issue the command "./isql 1111 dba dba" before "Server online at 1111" appears on screen -- the command ./isql 1111 dba dba should be issued in different session (screen, etc) as I want ./virtuoso-t to remain online while I execute my commands -- is there some way by which I may achieve the same

        Mon Aug 03 2015
17:08:49 { Loading plugin 1: Type `plain', file `wikiv' in `/home/jyotil/VirtuosoHugh/virtuosoInstalled/lib/virtuoso/hosting'
17:08:49   FAILED  plugin 1: Unable to locate file }
17:08:49 { Loading plugin 2: Type `plain', file `mediawiki' in `/home/jyotil/VirtuosoHugh/virtuosoInstalled/lib/virtuoso/hosting'
17:08:49   FAILED  plugin 2: Unable to locate file }
17:08:49 { Loading plugin 3: Type `plain', file `creolewiki' in `/home/jyotil/VirtuosoHugh/virtuosoInstalled/lib/virtuoso/hosting'
17:08:49   FAILED  plugin 3: Unable to locate file }
17:08:49 OpenLink Virtuoso Universal Server
17:08:49 Version 07.20.3213-pthreads for Linux as of Apr 10 2015
17:08:49 uses parts of OpenSSL, PCRE, Html Tidy
17:08:59 Database version 3126
17:09:00 SQL Optimizer enabled (max 1000 layouts)
17:09:01 Compiler unit is timed at 0.000687 msec
17:09:38 Roll forward started
17:09:38 Roll forward complete
17:09:52 Checkpoint started
17:09:54 Checkpoint finished, log reused
17:09:57 HTTP/WebDAV server online at 8890
17:09:57 Server online at 1111 (pid 4972)

For doing so I wrote the following shell script in (myScript.sh):

./virtuoso-t -f -c /home/var/lib/virtuoso/db/virtuoso.ini
./isql 1111 dba dba

However it appears that ./isql 1111 dba dba gets executed before "Server online at 1111" appears on screen. Is there some way in either python (by invoking the commands from python or c++ or using linux commands with which I may achieve the desired behaviour?

The command "./virtuoso-t -f -c /home/var/lib/virtuoso/db/virtuoso.ini" does not terminate, it remains online with the output "Server online at 1111" and in another terminal I execute queries on it using ./isql 1111 dba dba

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3 Answers 3

Reset to default
2

You need sequential commands. To achieve this, concatenate your commands with ;, like this:

 sleep 5s ; ls

You will notice that the directory listing happens after sleep finishes.

To match your specific example, run:

./virtuoso-t -f -c /home/var/lib/virtuoso/db/virtuoso.ini ; ./isql 1111 dba dba

To test if your server has started, adapt the following code to what you need. It uses netstat to check for opened ports on the host:

while netstat -lnt | awk '$4 ~ /:3306$/ {print "running"; system("ls"); exit 1}'; do sleep 2s; done

Note: i'm listening for a mysql server (3306 port - you need 1111)
Replace system("ls") with system("sh /full/path/to script")
print "running"; is optional (just textual status)

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5 Comments

or better, command1 && command2, so that the command2 won't be executed if command1 fails.
@fedorqui, good point, but as far as I know, && takes into account the returned value from the first command. And some of them also return 0 in case of success. This needs proper analysis. For a general "wait 'till first finished", i think ; does the trick
Thanks but my problem is the first command does not terminate..it remains there with the output "Server online at 1111 " and I execute "./isql 1111 dba dba" in another terminal..
I mean ./virtuoso-t starts a server..which is a database engine..it remains online with the output "Server online at 1111" on screen and using ./isql I can execute queries on this server...now I want to keep the server online in my script and issue queries using the command ./isql 1111 dba dba
@JannatArora, Using this updated answer, I was able to successfully wait for mysql to start, then run "ls" in the current directory. I think this suites your case.
2

You could reasonably wait until the line appears, by sending output to a file and grepping ...

#!/bin/bash
./virtuoso-t -f -c /home/var/lib/virtuoso/db/virtuoso.ini > log 2>&1 &
PID=$!
while [[ -d /proc/$PID && ! grep -q -m 1 "Server online at" log ]];
do
  sleep 1;
done
./isql 1111 dba dba

This:

  1. runs the server as a background process (&) and redirects its output to a file
  2. loops until the server emits the desired message to that file
  3. checks the server is alive, so a failed startup doesn't cause an infinite wait.

Edit:

Bash supports both the new [[ ... ]] and old [ ... ] conditional forms. The newer is preferred, but if your shell doesn't support it, try the old one.

It's possible your /bin/bash isn't really bash, I suppose, try running /bin/bash --version to see. If it's a simpler shell, #!/usr/bin/bash might work.

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7 Comments

Thanks..what does -d /proc/$PID do.. also why are we looking in log when the output is appearing on screen
ok..do we get the process id of the background process using PID=$! .. if not then what does it so...also we are we using -d /proc/$PID
Also when I execute this I am getting " [[: not found"
Yes my shell is bash i checked using echo $0 it gave /bin/bash. But I dont know why am I getting [[: not found. I did save the script using the same first line
should i use...while // -d /proc/$PID && ! grep -q -m 1 "Server online at" log //;
|
2

I came up with this, it reads the piped output line by line until it finds the one you are looking for.

#!/bin/bash

virtuoso-t -f -c /home/var/lib/virtuoso/db/virtuoso.ini 2>&1 | while read line
do
    echo $line
    if echo $line|grep 'Server online at 1111' > /dev/null; then
        isql 1111 dba dba
    fi
done
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