10-06-2009
Pointers on writing a unix script
Hi All,
I am writing a unix shell script. I have a file called Results.txt which stores 4 fields separated by pipe. i.e. a pipe delimited file. I want to loop through each record of this file and store each of these 4 fields into variables. I have read can be done through awk but I have never worked on unix. Any immediate help would be highly appreciated. Please help.
Regards,
Shweta
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pipe(2) System Calls pipe(2)
NAME
pipe - create an interprocess channel
SYNOPSIS
#include <unistd.h>
int pipe(int fildes[2]);
DESCRIPTION
The pipe() function creates an I/O mechanism called a pipe and returns two file descriptors, fildes[0] and fildes[1]. The files associated
with fildes[0] and fildes[1] are streams and are both opened for reading and writing. The O_NDELAY, O_NONBLOCK, and FD_CLOEXEC flags are
cleared on both file descriptors. The fcntl(2) function can be used to set these flags.
A read from fildes[0] accesses the data written to fildes[1] on a first-in-first-out (FIFO) basis and a read from fildes[1] accesses the
data written to fildes[0] also on a FIFO basis.
Upon successful completion pipe() marks for update the st_atime, st_ctime, and st_mtime fields of the pipe.
RETURN VALUES
Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error.
ERRORS
The pipe() function will fail if:
EMFILE More than {OPEN_MAX} file descriptors are already in use by this process.
ENFILE The number of simultaneously open files in the system would exceed a system-imposed limit.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Standard |
+-----------------------------+-----------------------------+
|MT-Level |Async-Signal-Safe |
+-----------------------------+-----------------------------+
SEE ALSO
sh(1), fcntl(2), fstat(2), getmsg(2), poll(2), putmsg(2), read(2), write(2), attributes(5), standards(5), streamio(7I)
NOTES
Since a pipe is bi-directional, there are two separate flows of data. Therefore, the size (st_size) returned by a call to fstat(2) with
argument fildes[0] or fildes[1] is the number of bytes available for reading from fildes[0] or fildes[1] respectively. Previously, the
size (st_size) returned by a call to fstat() with argument fildes[1] (the write-end) was the number of bytes available for reading from
fildes[0] (the read-end).
SunOS 5.10 23 Apr 2002 pipe(2)