Bash script for multiple output files

Question

I am attempting to use a bash script to create multiple output files from a file I have already created. As well as creating 10 output files I want to alter one piece of text in each of the files i'm creating from the original.

In the original document the starting lines read:

# For a single processor calculation
variable T equal 300 # Simulation temperature
variable salt equal 100.0 # Salt concentration [mM]

# Random number seed for Langevin integrator
variable random equal CPRAND

I want to change text that reads CPRAND to a random number in each file that I am creating.

The current bash script which I am using right now to try and do this is listed below:

for i in {0..10}
do
   cat me.sh | sed ’s/CPRAND/$((1 + RANDOM % 1000))/g‘ > “RunFile$(printf “%03d” “$i”).in”
done

I have not had any luck in getting it to work so far for multiple file creation. I appreciate any advice on this.

Thanks!

Please use four spaces in front of your file contents and code instead of the > (which is meant for quoting). You can also highlight the block and hit the {} button to properly format it. It's difficult to understand how your file is structured with the way your question is currently formatted. — JNevill
– JNevill, Commented Oct 23, 2018 at 13:11
I tried to correct your formatting. Please verify that the input and script as shown are are correct. Are your quotes in the script really “ instead of "? Also, what does I have not had any luck mean? Did you get errors? If so, show them. — Socowi
– Socowi, Commented Oct 23, 2018 at 13:13
And don't use cat here. sed can read directly from the source file. — Paul Hodges
– Paul Hodges, Commented Oct 23, 2018 at 15:22

Poshi · Accepted Answer · 2018-10-23 13:12:51Z

1

You need to interpret the content of the sed program, so the calculus you are doing gets processed by bash. Also, you can avoid the extra cat and the printf:

for i in {001..010}; do sed "s/CPRAND/$((1 + RANDOM % 1000))/" me.sh > RunFile${i}.in; done

answered Oct 23, 2018 at 13:12

Poshi

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potong · Accepted Answer · 2018-10-23 20:03:59Z

1

This might work for you (GNU sed & parallel):

parallel 'sed 's/CPRAND/'$((1+RANDOM%1000))'/g' >RunFile{}.in' me.sh ::: {000..010}

answered Oct 23, 2018 at 20:03

potong

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Bsquare ℬℬ · Accepted Answer · 2018-10-23 13:39:08Z

0

Because you are using instructions GNU/Bash must interpret, you must use double quotes, instead of single quote, at end, the working instruction can be:

for i in {0..10}
do
   cat me.sh | sed "s/CPRAND/$((1 + RANDOM % 1000))/g" > "RunFile$(printf "%03d" "$i").in"
done

answered Oct 23, 2018 at 13:39

Bsquare ℬℬ

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