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Full Discussion: lseek() equivalent
Top Forums UNIX for Dummies Questions & Answers lseek() equivalent Post 302469890 by DGPickett on Monday 8th of November 2010 01:43:03 PM
Old 11-08-2010
Where are these arrays, in C, shell, PERL, ???

Corona is saying you can put lines, each in one cell of an array shell variable, or the like.

In ksh, if you need the length of input without linefeeds, there are operators for string length. If you want part of the string, there are operators for sub-string extraction.
Code:
$ expr substr 1234567890 3 5      
34567
$

 

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lseek(2)							System Calls Manual							  lseek(2)

NAME
lseek - Moves read-write file offset SYNOPSIS
#include <sys/types.h> #include <unistd.h> off_t lseek ( int filedes, off_t offset, int whence ); STANDARDS
Interfaces documented on this reference page conform to industry standards as follows: lseek(): XSH5.0, XNS5.0 Refer to the standards(5) reference page for more information about industry standards and associated tags. PARAMETERS
Specifies a file descriptor obtained from a successful open() or fcntl() function. Specifies a value, in bytes, that is used in conjunc- tion with the whence parameter to set the file pointer. A negative value causes seeking in the reverse direction. The resulting file posi- tion may also be negative. Specifies how to interpret the offset parameter in setting the file pointer associated with the filedes parame- ter. Values for the whence parameter are: Sets the file pointer to the value of the offset parameter. Sets the file pointer to its cur- rent location plus the value of the offset parameter. Sets the file pointer to the size of the file plus the value of the offset parame- ter. DESCRIPTION
The lseek() function sets the file offset for the open file specified by the filedes parameter. The whence parameter determines how the offset is to be interpreted. The lseek() function allows the file offset to be set beyond the end of existing data in the file. If data is later written at this point, subsequently reading data in the gap returns bytes with the value 0 (zero) until data is actually written into the gap. By itself, the lseek() function does not extend the size of the file. RETURN VALUES
Upon successful completion, the resulting pointer location (the file offset), measured in bytes from the beginning of the file, is returned. If the lseek() function fails, the file offset remains unchanged, a value of (off_t) - 1 is returned, and errno is set to indi- cate the error. ERRORS
If the lseek() function fails, the file offset remains unchanged and errno may be set to one of the following values: The filedes parameter is not an open file descriptor. The whence parameter is an invalid value or the resulting file offset would be invalid. The filedes parameter is associated with a pipe (FIFO), a socket, or a multiplexed special file. The filedes parameter underlying the stream is associated with a socket. RELATED INFORMATION
Functions: fcntl(2), fseek(3), open(2), read(2), write(2) Standards: standards(5) delim off lseek(2)
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