Why does this not work in ksh?

[twilo202]

COUNT=`cat ${ALERT_LOG} | wc -l`
#COUNT=100
echo ${COUNT}
tail +${COUNT} ${ORACLE_ALERT}

The error is...

tail: cannot open input

It works fine if I use COUNT=100.

I can only presume that the tail command is interpretted as...

tail +`cat ${ALERT_LOG} | wc -l` ${ALERT_LOG}

although I have another script which does a similar thing and that works...ie...

LLC=`head -1 ${ADMIN_DIR}/${LLC_FILE}`

tail +${LLC} ${LOG_FILE} | grep ORA-

The only difference is that the LLC_FILE is a file with one line holding a number value.

 

[toolkit]

If you echo the tail line, you will see why:

echo tail +${COUNT} ${ORACLE_ALERT}
returns:
tail + <num> <file>

Notice the space between [tt]+[/tt] and [tt]<num>[/tt], which causes your problem.
A better solution is:

COUNT=$(expr $(wc -l < $ALERT_LOG))
tail +$COUNT $ORACLE_ALERT

Cheers, Neil