The C function for seeking in a file is called lseek(). Why ins't it called just seek()?

  • 2
    What does it return?
    – andy256
    Commented Jun 10, 2014 at 13:06
  • @andy256 off_t and if you want the 64 bit offset you use lseek64 Commented Jun 10, 2014 at 13:12
  • 2
    @ratchetfreak er ... thanks. The question was for the OP's benefit, not mine :-)
    – andy256
    Commented Jun 10, 2014 at 13:15
  • My guess is that it is an evolutionary thing, just remains from the past where was a distinction between long and int.
    – ysap
    Commented Jun 10, 2014 at 13:15
  • 3
    The extra character was added to make up for the missing one in creat(). (Actually, the L probably stands for logical.)
    – Blrfl
    Commented Jun 10, 2014 at 15:11

1 Answer 1


It appears that the 'l' in lseek means 'long', to differentiate from an old seek function in version 2 of AT&T Unix. This is an anachronism before the off_t type was introduced.

Supporting references:

http://infohost.nmt.edu/~eweiss/222_book/222_book/0201433079/ch03lev1sec6.html indicates:

The character l in the name lseek means "long integer." Before the introduction of the off_t data type, the offset argument and the return value were long integers. lseek was introduced with Version 7 when long integers were added to C. (Similar functionality was provided in Version 6 by the functions seek and tell.)

As noted at the foot of http://www.daemon-systems.org/man/lseek.2.html

 A seek() function appeared in Version 2 AT&T UNIX, later renamed into
 lseek() for ``long seek'' due to a larger offset argument type.
  • Intuition still works... :-)
    – ysap
    Commented Jun 12, 2014 at 1:08

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