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How can I print the numerical ASCII values of each character in a text file. Like cat, but showing the ASCII values only... (hex or decimal is fine).

Example output for a file containing the word Apple (with a line feed) might look like:

065 112 112 108 101 013 004
20

The standard command for that is od, for octal dump (though with options, you can change from octal to decimal or hexadecimal...):

$ echo Apple | od -An -vtu1
  65 112 112 108 101  10

Note that it outputs the byte value of every byte in the file. It has nothing to do with ASCII or any other character set.

If the file contains a A in a given character set, and you would like to see 65, because that's the byte used for A in ASCII, then you would need to do:

< file iconv -f that-charset -t ascii | od -An -vtu1

To first convert that file to ascii and then dump the corresponding byte values. For instance Apple<LF> in EBCDIC-UK would be 193 151 151 147 133 37 (301 227 227 223 205 045 in octal).

$ printf '\301\227\227\223\205\045' | iconv -f ebcdic-uk -t ascii | od -An -vtu1
  65 112 112 108 101  10
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hexdump, od, xxd, or $YOUR_FAVORITE_LANGUAGE can all do that.

% echo Apple | hexdump -C
00000000  41 70 70 6c 65 0a                                 |Apple.|
00000006
% echo Apple | perl -ne 'printf "%vd\n", $_' 
65.112.112.108.101.10
% echo Apple | clisp <( echo '(print (mapcar #'\''char-code (coerce (read-line *standard-input*) '\''list)))' )
(65 112 112 108 101)
% 
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  • Excellent answer, thankyou. Especially hexdump -C. Awarded to Stephane simply because his answer also resolved, and he was first (by just a hair), but both are excellent.
    – Mtl Dev
    Mar 8 '16 at 22:45
  • Yet another command: python -c "print open('file', 'rb').read().encode('hex')"
    – jfs
    Mar 9 '16 at 3:03
  • @J.F.Sebastian Better echo 'Apple' | python -c "import sys;print sys.stdin.read().encode('hex')"
    – heemayl
    Mar 9 '16 at 3:39
  • @heemayl : wrong. It may corrupt a binary file on Windows
    – jfs
    Mar 9 '16 at 3:41
  • @heemayl stdin uses the text mode by default that may translate newlines (os.linesep -> '\n')
    – jfs
    Mar 9 '16 at 3:47

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