fseek, ftell - reposition a file on a logical unit
integer function fseek (lunit, offset, from)
integer offset, from
integer function ftell (lunit)
lunit must refer to an open logical unit. offset is an offset in bytes
relative to the position specified by from. Valid values for from are:
0 meaning 'beginning of the file'
1 meaning 'the current position'
2 meaning 'the end of the file'
The value returned by fseek will be 0 if successful, a system error
code otherwise. (See perror(3F))
Ftell returns the current position of the file associated with the
specified logical unit. The value is an offset, in bytes, from the
beginning of the file. If the value returned is negative, it indicates
an error and will be the negation of the system error code. (See per-
4th Berkeley Distribution 18 July 1983 FSEEK(3F)