read values of variables from a table

osio · 01-08-2006, 06:56 PM

I'd like to write a shell script to manipulate images with some commands:

Quote:

convert -resize 1024x768 image.png
composite Mark1.png image.png watermarked.jpg
convert -gravity Center -draw "text 0,0 'Screen'" watermarked.jpg done.jpg

just by entering the name of the set of values

Quote:

#!/bin/bash

echo -n "Enter the image to convert: "
read image

echo -n "Enter the format to convert: "
read format

convert -resize [value1]x[value2] $image
composite [value3].png $image /tmp/watermarked.jpg
convert -gravity Center -draw "text 0,0 '[value4]'" /tmp/watermarked.jpg done.jpg

where the values are in a table:

format | value1 | value2 | value3 | value4
Large | 1024 | 768 | Mark1 | Screen
Regular| 800 | 600 | Mark1 | Monitor
Small | 320 | 240 | Mark2 | Monitor
Tiny | 160 | 120 | Mark2 | Mobile

How do I do that?
Thank you.
Osio

Hko · 01-09-2006, 06:38 AM

If the table is in a ASCII text file called "file.txt", do something like:

Code:

#!/bin/bash

IFS='|'
while read format value1 value2 value3 value4 ; do
        # do processing of each line here
        # variables: format, value1,.. will contain the
        # fields of each line processed in this loop.

        echo "format = $format"
        echo "value1 = $value1"
        echo "value2 = $value2"
        echo "value3 = $value3"
        echo "value4 = $value4"
        echo
done <file.txt

homey · 01-09-2006, 11:27 AM

I would get the spaces out of the table and maybe use a more standard separater like comma or tab.

Code:

format,value1,value2,value3,value4
Large,1024,768,Mark1,Screen
Regular,800,600,Mark1,Monitor
Small,320,240,Mark2,Monitor
Tiny,160,120,Mark2,Mobile

Here's what I have so far....

Code:

#!/bin/bash

read -p "Enter the image to convert: " image
read -p "Enter the format to convert: " format

value2=$(grep "$format" < file.txt | awk -F"," '{print$2}')
value3=$(grep "$format" < file.txt | awk -F"," '{print$3}')
value4=$(grep "$format" < file.txt | awk -F"," '{print$4}')
value5=$(grep "$format" < file.txt | awk -F"," '{print$5}')


convert -resize "$value2"x"$value3"  $image
composite $value4.png $image /tmp/watermarked.jpg
convert -gravity Center -draw "text 0,0 '$value5 '" /tmp/watermarked.jpg $image1.jpg

#Note: you probably can't use done.jpg as done is a reserved word.

osio · 01-10-2006, 09:20 AM

Yes, it works as expected.
The spaces and '|' separators are a bit cumbersome for larger tables, so I opted for the commas. I also need to sit down and try to understand 'IFS'.
If it helps to future readers, this is what I ended up with:

Quote:

#!/bin/bash

read -p "Enter the image to convert: " image
read -p "Enter the format to convert: " format

value2=$(grep "$format" < file.txt | awk -F"," '{print$2}')
value3=$(grep "$format" < file.txt | awk -F"," '{print$3}')
value4=$(grep "$format" < file.txt | awk -F"," '{print$4}')
value5=$(grep "$format" < file.txt | awk -F"," '{print$5}')

echo $image
convert -resize "$value2"x"$value3" $image /tmp/${image%%.*}.jpg
composite -dissolve 25% $value4.png /tmp/${image%%.*}.jpg /tmp/${image%%.*}_comp.jpg
convert -gravity Center -draw "text 0,0 '$value5 '" /tmp/${image%%.*}_comp.jpg ${image%%.*}2.jpg
display ${image%%.*}2.jpg
exit

Thanks a lot Hko and homey.
Osio

bigearsbilly · 01-10-2006, 10:27 AM

ugh that's nasty (sorry!)
four pipelines of grep into awk?

why didn't you use the nice elegant solutions?

as an aside, you can use set to set the $n variables:

Code:

billym.>line='one two three four'
billym.>set -- $line
billym.>echo $4 $3 $2 $1         
four three two one

homey · 01-10-2006, 11:19 AM

Quote:

why didn't you use the nice elegant solutions?

I know my programming skills are nonexistant/suck.
Could you post your script so I can learn from it?

homey · 01-10-2006, 07:48 PM

If it was a snake, I'd be in trouble.
Thanks bigearsbilly!

Code:

Large 1024 768 Mark1 Screen
Regular 800 600 Mark1 Monitor
Small 320 240 Mark2 Monitor
Tiny 160 120 Mark2 Mobile

Code:

#!/bin/bash

read -p "Enter the image to convert: " image
read -p "Enter the format to convert: " format

line=$(grep "$format" < file.txt)
set -- $line

echo $image
convert -resize "$2"x"$3" $image /tmp/${image%%.*}.png
composite -dissolve 25% $4.png /tmp/${image%%.*}.png /tmp/${image%%.*}_comp.png
convert -gravity Center -draw "text 0,0 '$5 '" /tmp/${image%%.*}_comp.png ${image%%.*}2.png
display ${image%%.*}2.png
exit

bigearsbilly · 01-11-2006, 02:52 AM

I think HKO's was the nicest looking!

also, why the read -p
that's usually used for a spawned background process,
like:

Code:

find . -type d |&
# blah
read -p

sorry to be a moaner