Shell script to read two values from file and insert them into a command

Question

I have a text file, say, input.txt and I want to run a command and write the output to another text file, say, output.txt. I need to read values from input.txt, each value is in a line, then I need to insert them in the command then write the result in output.txt file. I tried the following and it works fine with me:

for i in `cat input.txt`; do command -m $i -b 100; echo $i; >> output.txt; done

Now, I need to make some improvements over this but I have little experience in Linux so I need some help.

What I need to do is: 1) Before each command result, I want to insert the value of i separated by comma. For example:

i1,result1 
i2,result2
i3,result3

2) I need to change the second fixed value that I used in my command from a fixed value (100) to a value read from input.txt. So, the new input file which contains two values, say, newinput.txt is as the following:

i1,value1
i2,value2
i3,value3

ams · Accepted Answer · 2012-12-04 14:56:33Z

1

Try this, in bash:

IFS=','
while read i val; do
  echo -n "$i,"
  command $i $val
done < input.txt > output.txt

answered Dec 4, 2012 at 14:56

ams

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4 Comments

user1810868 Over a year ago

This is what I get: bash: syntax error near unexpected token 'do'

user1810868 Over a year ago

When I removed the ; before do, I got: while: command not found

user1810868 Over a year ago

I solved the issue. I was writing the script in the terminal. When I wrote it to a file and then execute it, it worked.

William Pursell Over a year ago

@user1810868 Typing the script to the terminal is not the issue. Rather, the issue is (probably) that the shell you are using when entering text is a csh variant.

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