Snips of Scripts

• exec -replaces the running process with a new one
• exit n -quits the shell with exit status n
• export -makes variables available to spawned shells

• IF, WHILE, DO

  if [ -z "$" ]; then
    while [ -z "$" ]
    do
    ....(some code)...
    done 
  fi
  

• FOR, DO, DONE

  for i in  word1 word2 ...wordn
  do
    action involving $i (which = word)
  done
  



• AWK & SED

  NEW_VARIABLE="`/sbin/ifconfig -a|grep -A 2 eth0|awk '/inet/ { print $2 }'|sed -e s/addr://`"
  



• MAIL Notification

  # build the Message & Subject variables
     echo "No major canges in disk use on $HOSTNAME" > $MESSAGE
     echo "  " >> $MESSAGE
     echo "`cat $DISKUSE`" >> $MESSAGE
     echo "$HOSTNAME - Disk Space Report" > $SUBJECT
  
  # send the message to address $EMAIL
  echo "`cat $MESSAGE`" | mail -s "`cat $SUBJECT`" $EMAIL
  



• Test if File Exists with Non-Zero Size

  if [ -s $DIFFTEST ] ;then
  



• Test for Exact Equal (of number value)

  if [ $SCHEDULED == $ACTUAL ] ;then
  



• Get IP Address

  # get external address from by greping ifconfig 
  EXIP="`ifconfig -a|grep -A 2 $EXIF|awk '/inet/ { print $2 }'\
     |sed -e s/addr://`"
  



• Get Broadcast Address

  EXBCAST="`ifconfig -a|grep -A 2 $EXIF|awk '/inet/ { print $3 }'\
    |sed -e s/Bcast://`"
  



• Get DNS Server IP's

  # get dns servers from resolv.conf file
  # first line is path, next 3 are dns servers
  NAMED1="`cat /etc/resolv.conf|grep -n nameserver|grep 2:\
   |sed -e s/nameserver//|sed -e s/2://`" 
  
  NAMED2="`cat /etc/resolv.conf|grep -n nameserver|grep 3:\
   |sed -e s/nameserver//|sed -e s/3://`"
  
  NAMED3="`cat /etc/resolv.conf|grep -n nameserver|grep 4:\
   |sed -e s/nameserver//|sed -e s/4://`"
  



• Remove Spaces from Filenames

  for x in `ls -1|sed -e s/"\ "/_/g`;do mv "`echo $x|sed -e s/_/"\ "/g`" ${x};done