Commandline hexdump with ASCII output? [closed]

hexdump -C does what you want.

# hexdump -C /etc/passwd
00000000  72 6f 6f 74 3a 78 3a 30  3a 30 3a 72 6f 6f 74 3a  |root:x:0:0:root:|
00000010  2f 72 6f 6f 74 3a 2f 62  69 6e 2f 62 61 73 68 0a  |/root:/bin/bash.|
00000020  64 61 65 6d 6f 6e 3a 78  3a 31 3a 31 3a 64 61 65  |daemon:x:1:1:dae|
00000030  6d 6f 6e 3a 2f 75 73 72  2f 73 62 69 6e 3a 2f 62  |mon:/usr/sbin:/b|
00000040  69 6e 2f 73 68 0a 62 69  6e 3a 78 3a 32 3a 32 3a  |in/sh.bin:x:2:2:|
00000050  62 69 6e 3a 2f 62 69 6e  3a 2f 62 69 6e 2f 73 68  |bin:/bin:/bin/sh|
...

The vim editor usually (?) includes the tool xxd.

$ xxd `which xxd` | head -n 10
0000000: 7f45 4c46 0201 0100 0000 0000 0000 0000  .ELF............
0000010: 0200 3e00 0100 0000 400a 4000 0000 0000  ..>.....@.@.....
0000020: 4000 0000 0000 0000 f035 0000 0000 0000  @........5......
0000030: 0000 0000 4000 3800 0800 4000 1b00 1a00  [email protected]...@.....
0000040: 0600 0000 0500 0000 4000 0000 0000 0000  ........@.......
0000050: 4000 4000 0000 0000 4000 4000 0000 0000  @.@.....@.@.....
0000060: c001 0000 0000 0000 c001 0000 0000 0000  ................
0000070: 0800 0000 0000 0000 0300 0000 0400 0000  ................
0000080: 0002 0000 0000 0000 0002 4000 0000 0000  ..........@.....
0000090: 0002 4000 0000 0000 1c00 0000 0000 0000  ..@.............

hexdump itself will show both hex and ascii side-by-side:

$ date | hexdump -v -C
00000000  54 68 75 20 4d 61 79 20  20 31 20 31 36 3a 30 30  |Thu May  1 16:00|
00000010  3a 32 35 20 50 44 54 20  32 30 31 34 0a           |:25 PDT 2014.|
0000001d

man hexdump explains:

 -C      Canonical hex+ASCII display.  Display the input offset
         in hexadecimal, followed by sixteen space-separated,
         two column, hexadecimal bytes, followed by the same
         sixteen bytes in %_p format enclosed in ``|'' charac‐
         ters.

         Calling the command hd implies this option.