Shell Programming and Scripting

[[ ! -z $line ]] && { dosomething_else ; } || { dosomething ; }

if [[ ! -z $line ]]; then
     cmd1
     cmd2 
     ...
else
     cmd3
     cmd4
     ...
fi

#!/bin/ksh

nawk '
  # create an variable "idx" which is a concatenation of the first 5 fields in a record/line
  # as we read the file line by line
  {idx=$1 FS $2 FS $3 FS $4 FS $5}
  {
    # see if "idx" is in array "a" - array "a" is indexed by the value of "idx"
    if (!(idx in a))
      print 0 ":" $0
    else
      # if "idx" is already in "a", check if the stored value (a[idx]) is less than the
      # last field ($NF) of the current record/line. If it"s, we see the "increase" in value
      # If so, output the current line (print $0)
      if (a[idx]<$NF)
         print 1 ":" $0
    # store the last field ($NF) of the current record in aarray "a" indexed by "idx"
    a[idx]=$NF
  }' myDiffFile | while IFS=: read smth line
do
  # read the output of "nawk" and do "doSomething" with the read line
  if [ "${smth}" -eq 1 ]; then
     echo "doSomething with [$line]"
  else
     echo "doSomethingElse with [$line]"
  fi
done

flag=0
...
.. | while read line
do
flag=1
echo "doSomething with [$line]"
done
if [ "$flag" -eq 0 ] ; then
   echo "doSomethingElse with [noline]"
fi

doSomethingElse with [AAA BBB CCC DDD EEE 10]
doSomething with [AAA BBB CCC DDD EEE 11]
doSomethingElse with [PPP QQQ RRR SSS TTT 5]
doSomethingElse with [VVV WWW XXX YYY ZZZ 2]

#!/bin/ksh

nawk '
  # create an variable "idx" which is a concatenation of the first 5 fields in a record/line
  # as we read the file line by line
  {idx=$1 FS $2 FS $3 FS $4 FS $5}
  {
    # see if "idx" is in array "a" - array "a" is indexed by the value of "idx"
    if (!(idx in a) && FNR>1)
      print 0 ":" $0
    else
      # if "idx" is already in "a", check if the stored value (a[idx]) is less than the
      # last field ($NF) of the current record/line. If it"s, we see the "increase" in value
      # If so, output the current line (print $0)
      if (a[idx]<$NF || FNR==1)
         print 1 ":" $0
    # store the last field ($NF) of the current record in aarray "a" indexed by "idx"
    a[idx]=$NF
  }' myDiffFile| while IFS=: read smth line
do
  # read the output of "nawk" and do "doSomething" with the read line
  if [ "${smth}" -eq 1 ]; then
     echo "doSomething with [$line]"
  else
     echo "doSomethingElse with [$line]"
  fi
done

< AAA BBB CCC DDD EEE 123
> PPP QQQ RRR SSS TTT 111
> VVV WWW XXX YYY ZZZ 333
> AAA BBB CCC DDD EEE 124

doSomethingElse with [< AAA BBB CCC DDD EEE 123]
doSomethingElse with [> PPP QQQ RRR SSS TTT 111]
doSomethingElse with [> VVV WWW XXX YYY ZZZ 333]
doSomethingElse with [> AAA BBB CCC DDD EEE 124]

doSomething with [> PPP QQQ RRR SSS TTT 111]  # first occurrence
doSomething with [> VVV WWW XXX YYY ZZZ 333]  # first occurrence
doSomething with [> AAA BBB CCC DDD EEE 124]  # last counter field increased from 123 to 124