#!/bin/ksh

#
# Some script syntax examples:

#
# reading output from one program to use in a variable
ps -eaf | grep httpd | while read USER PID PPID THEREST; do
	grep "error: $PID" /var/adm/somelogfile
done

#
# The problem with the previous example is that you can't do
# something with standard out in the middle of the loop, since 
# you are already using standard out.   Another way to do it is this:
ps -eaf | grep httpd | while read USER PID PPID THEREST; do
	PIDLIST="$PIDLIST $PID"
done
for CURPID in $PIDLIST; do
	grep "error: $PID" /var/adm/somelogfile >> /tmp/someotherlog
done

#
# You can also format the output of "ps" the way you want using the 
# "-o" option.
ps -eaf -o pid -o comm | grep "httpd" | while read PID CMD; do
	kill $PID
done

#
# You can also use program output this way:
# Suppose you want to see what the permissions and ownerships were on some
# command that was in your path:	
ls -al `which su`

#
# Or suppose you wanted to save a date/time stamp so that you could use 
# it multiple times:
DTIME=`date +"%m%d%y.%H%M"`
mv log1 log1.$DTIME
mv log2 log2.$DTIME

#
# Some examples of the "test" operation:
# -r  file exists and is readable
# -w  file exists and is writable
# -x file exists and is executable
# -f  file exists and is a regular file. (not a dir)
# -d  file is a directory
# -h  file is a symbolic link
# -c  file is a character special file
# -b  block special file
# -p  named pipe
# -u  setuid file
# -g  setgid file
# -k  sticky bit set
# -s  file exists and has a size greater than 0
# -z  test for zero len string
# -n  non-zero length string
#
# Numeric test operators:
# -lt less than
# -le less than or equal to
# -gt greater than
# -ge greater than or equal to
# -eq equal to
# -ne not equal to
#
# String test operators
# = equal
# != not equal
# > greater than
# < less than
# 
# boolean operators
# -a and
# -o or
# ! not
#
if [ -f /tmp/myfile ]; then
	cat /tmp/myfile
fi

#
# elif structure
if [ ! -f $FILE ]; then	
	echo "No such file $FILE"
elif [ ! -r $FILE ]; then
	echo "$FILE not readable"
else 
	echo "File is readable"
fi


#
# Processing command line options:
while [ $# -ge 2 ]; do
	case $1 in 
	-f) FILE=$2
		shift 2
		;;
	-d) DEVICE=$2
		shift 2
		;;
	*) echo "usage: $0 [-f <filename>] [-d <device name>]"
		exit 1
		;;
	esac
done

#
# This is an example of of subroutine definition and call
hup_daemon () {
DAEMON="$1"
ps -e -o pid,comm | grep "$DAEMON" | while read PID COMM; do
	echo "send HUP to $PID $COMM"
	kill -HUP $PID
done
};

hup_daemon inetd

# Writing data to syslog
/usr/local/bin/someCommand > /var/adm/someCommand.log
if [ $? -eq 0 ]; then
	logger -p user.notice "NOTE:  someCommand worked just fine"
else
	logger -p user.err "ERROR: someCommand had a problem"
fi

#sending a file as an attachment in email
uuencode /var/adm/someCommand.log someCommand.log | mailx -s "Log file from
someCommand" someUser@somedomain.com