5 Essential Unix Commands You Probably Missed (and How to Use Them)

1. man ascii

Displays the ASCII character table in octal, hexadecimal and decimal columns. Useful as a quick reference without leaving the terminal.

ASCII(7)          BSD Miscellaneous Information Manual          ASCII(7)
NAME
ascii -- octal, hexadecimal and decimal ASCII character sets
DESCRIPTION
The octal set:
000 nul  001 soh  002 stx  003 etx  004 eot  005 enq  006 ack  007 bel
010 bs   011 ht   012 nl   013 vt   014 np   015 cr   016 so   017 si
020 dle  021 dc1  022 dc2  023 dc3  024 dc4  025 nak  026 syn  027 etb
030 can  031 em   032 sub  033 esc  034 fs   035 gs   036 rs   037 us

Manual page: http://linuxcommand.org/man_pages/ascii7.html

2. cal

Shows a calendar for a specified month or year. By default it prints the current month.

August 2013
Su Mo Tu We Th Fr Sa
          1  2  3
 4  5  6  7  8  9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
25 26 27 28 29 30 31

Options are documented in the manual page: http://linuxcommand.org/man_pages/cal1.html

3. xxd

Creates a hexadecimal dump of a file and can also convert a hex dump back to binary. The -i flag outputs a C‑style array, which is convenient for embedding binary data in source code.

0000000: 83ff 0010 8d01 0408 d301 0408 a540 0408  .............S..
0000010: d701 0408 d901 0408 db01 0408 0000 0000  ................
... (truncated) ...

Generate a C array:

xxd -i data.bin

unsigned char data_bin[] = {
  0x6d, 0x61, 0x64, 0x65, 0x20, 0x79, 0x6f, 0x75,
  0x20, 0x6c, 0x6f, 0x6f, 0x6b, 0x0a
};
unsigned int data_bin_len = 14;

Manual page: http://linuxcommand.org/man_pages/xxd1.html

4. ssh

Secure Shell provides encrypted remote login and a suite of auxiliary tools.

File transfer with scp.

X‑forwarding: run GUI applications on a remote host and display them locally.

Port forwarding (local and remote) to tunnel traffic through the encrypted channel.

SOCKS proxy: route arbitrary TCP traffic via the remote host.

Agent forwarding: load private keys once and reuse them for subsequent connections.

Manual page: http://www.manpagez.com/man/1/ssh/

5. mdfind

macOS-specific command that queries the Spotlight index. It is faster than find for many searches because it uses the pre‑built index.

mdfind -name homebrew
/usr/local/Library/Homebrew
/Users/job/Library/Logs/Homebrew

Manual page: http://www.manpagez.com/man/1/mdfind/