scripting question

[soji]

Hi experts,
Im trying to write a script either in awk or in ksh to read in a text file with a format like shown below:
......start....
sht 2 3 4
trc 4 5 5
trc 3 3 2
trc 2 3 4
trc 3 4 1
trc 1 3 6
trc 3 3 5
trc 4 3 1
trc 2 3 5
sht 1 6 3
trc 4 5 5
trc 3 3 2
trc 2 3 4
trc 3 4 1
trc 1 3 6
trc 3 3 5
trc 4 3 1
trc 2 3 5
.........end.........
It is a really long file with similar format. All I want to do is to read in the file and print the line that starts with "sht" and every fourth line that starts with "trc"

Could somebody help me please

Thanks in advance

[Robin Wakefield · Accepted solution]

Hi,

awk '/^sht/ || (NR%4 == 0 && /^trc/){print}' filename

should do the trick (if I interpret the trc requirement correctly).

rgds, Robin

[Stefan Farrelly]

let x=0
cat t|while true
do
read A B C D
[ "$A" = "" ] && exit
[ "$A" = "sht" ] && echo $A $B $C $D
if [ "$A" = "trc" ]
then
let x=$x+1
if [ $x -eq 4 ]
then
echo $A $B $C $D
let x=0
fi
fi
done

where t (on 2nd line in cat t) is the name of the input file with all your data in.

[soji]

Thanks for the quick reply.
It is very close.

I actually want to print every fourth occurence of lines begining with "trc"

Thanks a lot again

[Robin Wakefield]

OK, well try:

awk '/^sht/{print}/^trc/{count++;if (count==4){print;count=0}}' file

this resets the counter after 4 occurrences of trc at the beginning of the line.

rgds, Robin

[Steve Steel]

Hi


file=$1
typeset -i x=1
cat $file|while read a b c d
do
case $a in
sht) echo $a $b $c $d ;;
trc) if [ "$x" -eq "4" ]
then
let x=1
echo $a $b $c $d
else
typeset -i x=$x+1
fi ;;
esac
done


Steve Steel

[H.Merijn Brand (procura]

# perl -ne'/^sht/||(/^trc/&&++$t%4==0)and print' log
sht 2 3 4
trc 3 4 1
trc 2 3 5
sht 1 6 3
trc 3 4 1
trc 2 3 5


Enjoy, have FUN! H.Merijn

[soji]

Thank you All for the replies and help...Especially Robin who was quick...I chose you second solution. By the way what does the NR%4 do in your first solution what does modulus do in awk?

thanks

[Yogeeraj_1]

hi,
FYI:

x % y
Remainder. The quotient is rounded toward zero to an integer, multiplied by y and this result is subtracted from x. This operation is sometimes known as "trunc-mod." The following relation always holds:
b * int(a / b) + (a % b) == a

One possibly undesirable effect of this definition of remainder is that x % y is negative if x is negative. Thus,
-17 % 8 = -1


hth
Yogeeraj