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Detect if script starts from queue

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# 8  
Old 08-09-2012
Quote:
Originally Posted by Corona688
This can be defeated by redirecting into the script a la < /dev/null.
What do you mean with "redirecting into the script" ? Smilie
# 9  
Old 08-09-2012
what exactly doesn't work?
this works as a stand-alone script - lord.sh
Code:
#!/usr/bin/ksh

if [ -t 0 ] && [ "$#" -eq 0 ] ; then
  echo "WARNING: This script cannot start from command line, use parameters instead (interactive mode)!"
  exit
fi;

echo 'param found - good'

# 10  
Old 08-09-2012
This appears to work better:

Code:
# Prevent error message spam
exec 2>/dev/null

if ! exec 5</dev/tty
then
        echo "No terminal"
else
        echo "Terminal"
fi

# 11  
Old 08-09-2012
Quote:
Originally Posted by Lord Spectre
What do you mean with "redirecting into the script" ? Smilie
Exactly what I said.

If they run it like ./script < /dev/null then FD0 will not be a terminal, and your check will be bypassed.

To prevent that kind of trickery, go direct to the source. If you can open /dev/tty, you have an interactive terminal. If you can't, you don't.

Unfortunately every failure will cause an error message unless you redirect stderr temporarily.
Last edited by Corona688; 08-09-2012 at 03:25 PM..
This User Gave Thanks to Corona688 For This Post:
Lord Spectre
# 12  
Old 08-10-2012
Quote:
Originally Posted by Corona688
This appears to work better:

Code:
# Prevent error message spam
exec 2>/dev/null

if ! exec 5</dev/tty
then
        echo "No terminal"
else
        echo "Terminal"
fi

Thanks Corona, but unfortunately I already use STR & STOUT in my script:
Code:
exec 1>>/applog/script_$(date +"%Y%m%d").log; exec 2>>/applog/script_$(date +"%Y%m%d").log
....
....
  exec 1>&5
  exec 2>&6
echo "STDERR & STOUT come back to screen"
....
....

I believe your caode overlaps mine...
# 13  
Old 08-10-2012
Then you already know how to preserve and restore file descriptors. The important thing is that you get rid of the error message that moment, afterwards you can put stderr right where it was.

And you don't have to use 5 in my code. Make it 7 since you're already using 5 and 6.
This User Gave Thanks to Corona688 For This Post:
Lord Spectre
# 14  
Old 08-16-2012
Corona, sorry if I resume the thread, but finally I had time to test your code.
Code:
CheckInteractive ()
{
if exec 7</dev/tty
then
  bold=`tput bold`
  normal=`tput sgr0`
  echo ; echo "${bold}WARNING: SCRIPT cannot start from command line, use parameters instead (interactive mode)!${normal}"
  exit                 
fi
}

CheckInteractive
Rest of the script

This works perfect when on terminal, but generate error when start from crontab and the rest of the script is not executed. This is the mail content it generated every time script starts from crontab:

Code:
TERM environment variable not set.
/tmp/test.sh[345]: /dev/tty: cannot open [No such device or address]

How can I handle that ?

Thanks
Lucas
Last edited by Lord Spectre; 08-16-2012 at 07:34 AM..
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