topic Duplicating Characters in Operating System - HP-UX

Duplicating Characters

Paul Murray_4 — Wed, 21 Jul 2004 09:43:53 GMT

Can anyone tell me if there is an easy way to echo out a given number of duplicate characters to the screen (or even better, into a variable) !

I want to be able to echo a set number of spaces based upon the width of the screen as set in ${LINES}, from within a ksh script.

I've tried a quick counting loop to build the text, but this seems to really slow up my script.

I know there is probably a good way to do this with awk/sed etc, but I just cannot think of the best way to do it !!

Any help will be greatly appreciated (as always !!)

Thanks,
Paul.

Re: Duplicating Characters

Mike Stroyan — Wed, 21 Jul 2004 10:10:49 GMT

Spaces are particularly easy because you can use a printf field width.

myvar=$(printf "%${LINES}s" " ")

That uses the printf command with a blank string printed into a field of $LINES characters.

Re: Duplicating Characters

Paul Murray_4 — Wed, 21 Jul 2004 10:13:30 GMT

Mike, what can I say .....

YOU ARE A STAR !!!!!

Thanks !
Paul.

Re: Duplicating Characters

curt larson_1 — Wed, 21 Jul 2004 10:19:00 GMT

sounds like something that might be done with printf

this will right justify your text

cat file |
while read text
do
printf '%${LINES}s\n' $text
done

#print "x" number of spaces
printf '%${x}s' " "

of course the important information of how many spaces (other then based on LINES) and where the spaces should be, you left out of your question.

maybe if you provided some sample text to illustrate what your trying to accomplish better suggestions could be provided.

Re: Duplicating Characters

Hein van den Heuvel — Wed, 21 Jul 2004 10:19:20 GMT

if it is only spaces you are after, then you are lucky, as printf from anywhere (awk, shell) can nicely do a variable length empty field:

# awk 'END{printf ("test%*stest\n",40," ")}' /dev/null

For long series of other characters PERL has a neat 'x' function

#perl -e 'print "*"x10 . "\n"'
**********
# perl -e 'print "*"x20 . "\n"'
********************

fwiw,
Hein.

Re: Duplicating Characters

Paul Murray_4 — Wed, 21 Jul 2004 10:22:03 GMT

Thanks Curt. One small question, just to up-spec my own knowledge really .....

If I wanted to print hash marks instead of spaces, what would I need to change ?

Regs,
Paul.

Re: Duplicating Characters

curt larson_1 — Wed, 21 Jul 2004 10:43:56 GMT

If I wanted to print hash marks instead of spaces, what would I need to change ?

the easy answer is perl, where you could do:
print "#" x $num;

but to avoiding calling perl for each line of your text, you'd want to do everything within perl or

#make a long variable with hashes
# just pick a number bigger then your going to need
myvar=$(perl -e 'print "#" x 256;')

then use printf within your shell script to truncate the variable to the length you want

printf "%{Len}s" $myvar

that way you'll only call perl once.

of course a simply while loop might be even faster then calling perl

x="#"
y=10
while (( y > 0 ))
do
x="$x$x"
y=$(( $y = 1 ))
done
# x is now a long string of #'s

Re: Duplicating Characters

curt larson_1 — Wed, 21 Jul 2004 10:59:26 GMT

I hope you caught my mistake where
x="$x$x"
y=$(( $y = 1 ))

should really be

x="$x$x"
y=$(( $y - 1 ))

and if your really doing some serious text formatting, using perl is the way to go. it is a feature rich tool which is so much better then the shell. i.e. shell text formatting has just implemented the printf function in the past few years, where perl was designed for formattng text.

Re: Duplicating Characters

Paul Murray_4 — Wed, 21 Jul 2004 11:04:25 GMT

Hi Curt,

Thanks again for the help. The text formatting part of the script is pretty minor, so I ended up cheating rather than using perl.

MYVAR="$(echo "$(printf "%${LINES}s" " ")" | sed 's/ /\#/g')"

Thanks again (to all !) for your help.

Paul.

Re: Duplicating Characters

Mike Stroyan — Wed, 21 Jul 2004 16:12:04 GMT

sed is a rather heavy general-case tool for replacing characters. The tr command specializes in it.

MYVAR="$(printf %${LINES}s ' ' | tr ' ' '#')"

Re: Duplicating Characters

Paul Murray_4 — Thu, 22 Jul 2004 09:48:04 GMT

Good call !! Thanks Mike !