Runinng command on each line and export in the same way

Question

I have multiple strings in a file, for each one I need to run a command and export the results. Here is an illustration:

file.txt

string1
string2
string3

I'm running:

while read in; do sigtool --hex-dump "$in"; done < file.txt > test.txt

This provides the following output:

737472696e6731a737472696e6732a737472696e6733

I would like the output to be separated by line like below:

737472696e6731
737472696e6732
737472696e6733

How can I achieve that?

Answer 1

You want newlines. So output newlines.

while read in; do sigtool --hex-dump "$in"; echo; done < file.txt > test.txt

Note the added echo command.

Mind you, the first place I would check is the sigtool man page to see if there's an option to output trailing newlines.

---

Okay, I wrote the above without actually getting sigtool (from the clamav package) and testing it. Now I have done so.

The code you wrote doesn't work, at least not with clamav-0.99.2-3.el6.x86_64. sigtool accepts input on its standard input. It has no option to accept and translate command line arguments.

So what you really want is, dropping back to the old favorite non-visual editor ex:

printf '%s\n' 'g/^/.!tr -d \\n | sigtool --hex-dump' %p | ex file.txt > test.txt

Demonstration:

$ cat file.txt 
string1
string2
string3
$ printf '%s\n' 'g/^/.!tr -d \\n | sigtool --hex-dump' %p | ex file.txt > test.txt
$ cat test.txt 
737472696e6731
737472696e6732
737472696e6733
$ 

Explanation:

Globally (for each line matching regex /^/, which is every line) filter each line (.!) through the shell pipeline tr -d \\n | sigtool --hex-dump, then print (p) the entire buffer (%) to standard output, and don't save changes to file.txt.

---

Another approach, using Awk:

awk -v p='sigtool --hex-dump' '
  {printf "%s", $0 | p; close(p); printf "\n"}
' file.txt > test.txt

Answer 2

Alternative brute force:

cat test.txt | sigtool --hex-dump | sed 's/0a/\n/g' > gzout.hex

Just convert the hex newlines back as long as you are dealing with an ASCII text file.

(If you're dealing with non-ASCII you may have 0a appearing in the hex dump without signifying a newline in the input.)