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I am new to Linux. I observed some of the binary files and configuration file name s end with a d. What is reason for putting a d at the end of the file name?

Like httpd, ospfd, pppd, syslogd, telnetd, pptpd, and dhcpd.

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2 Answers 2

up vote 56 down vote accepted

They are daemons (Computing) – as in "workers behind the curtain".

http   Daemon - Hypertext Transfer Protocol Daemon
ospf   Daemon - Open Shortest Path First Daemon (89)
ppp    Daemon - Point-to-Point Protocol Daemon
syslog Daemon - Syslog Daemon
telnet Daemon - Telnet server Daemon
pptp   Daemon - Point-to-Point Tunneling Protocol Daemon
dhcp   Daemon - Dynamic Host Configuration Protocol Daemon

All depending on how you interpret the word they can definitively also be demons.

As Wikipedia and Take Our Word For It explains; the words is taken from Maxwell's daemon

Courtesy of Htkym Creative Commons

Maxwell's_demon.svg Htkym CC, Wikipedia

"an imaginary agent which helped sort molecules of different speeds and worked tirelessly in the background."


Else the usage of the word is somewhat in these lines:

daemon: spirit      (polytheistic context)
demon : evil spirit (monotheistic context)

Fix#1:

And as pointed out by the good Mr. @Michael Kjörling, to emphasize: "Of course, just because the executable's name ends in d doesn't mean it is a daemon."

sed    Stream Editor
dd     Data Description 
chmod  Change file mode bits 
xxd    Hex Dump
find   Find

etc. are examples of frequently used tools ending in d. Then again that would not be an added suffix as in sedd.

ls /usr/bin/*d /bin/*d

Though; typically daemons have the letter d appended at the end.

telnet vs telnetd

Another writeup on the subject of *Nix Daemons.

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13  
find - the daemon with fins... –  Tobias Kienzler Apr 16 '13 at 11:08
4  
Oh my God! I'd have never guessed that it was taken from Maxwell's daemon! –  Bakuriu Apr 16 '13 at 11:30
3  
Sounds like you made an UUOC with ls | cat. You can use the one-line option: ls -1. –  lolesque Apr 16 '13 at 12:38
9  
ld - linker daemon; pwd - print whereabouts daemon; head - hold everything after (so many lines) daemon; find - flatten inscrutable nesting daemon. –  Kaz Apr 16 '13 at 16:01
2  
@TobiasKienzler: Ah. Always thought that was Linus Torvalds evil twin. Also a Fin. –  Sukminder Apr 16 '13 at 18:26
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They're daemons. Simple as that.

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instead of "They're", i'd put "Most are" ;) –  Olivier Dulac Apr 18 '13 at 12:47
1  
Fair comment @OlivierDulac, but the ones he explicitly listed all actually are. –  tink Apr 18 '13 at 18:04
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