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



I'm running:

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

This provides the following output:


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


How can I achieve that?

  • What happens when you run the code you have given?
    – jesse_b
    Dec 22, 2017 at 2:33
  • This > 737472696e6731a737472696e6732a737472696e6733, it will print in one line, with a space.
    – mirsad
    Dec 22, 2017 at 2:35
  • I'm sure this isn't the proper way of doing it but what about: while read in; do echo -e "$(sigtool --hex-dump "$in")\n"; done < file.txt > test.txt?
    – jesse_b
    Dec 22, 2017 at 2:48
  • Do you have to use sigtool for this? have you considered something like perl -lpe '$_ = unpack("H*",$_)' file.txt instead? Dec 22, 2017 at 3:02
  • Note this won't be a standard format at all. Have you considered using xxd, which can do conversions in either direction?
    – Wildcard
    Dec 22, 2017 at 3:29

2 Answers 2


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


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


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
  • I suspect that will still unpack the newlines though (resulting in trailing a bytes visible in the OP's concatenated output) Dec 22, 2017 at 3:05
  • @steeldriver, okay, okay. I actually did the research this time and tested it. :P
    – Wildcard
    Dec 22, 2017 at 3:25
  • @Wildcard, great job! Exactly what I needed.
    – mirsad
    Dec 22, 2017 at 22:24

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.)

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