hey guys this is my first post here, heard a lot about these forums. Iam urgently in need of a command which would help me accomplish the following , for example a file has these contents:
211 61 2007-06-26 13:47:32
211 61 2007-06-26 09:53:43
211 61 2007-06-26 15:25:14
211 61 2007-06-26... (5 Replies)
Hi,
I want to use egrep to match this expression in my file. The expression begins with the word SCHEDULE and ends with PFTDGNIN. In between these 2 words there can be anything.
EX: Line1: SCHEDULE NWERRR#PFTDGNIN
Line2: FOLLOWS NWD@AAS#PFTDGNIN
So as a result of the egrep command... (1 Reply)
I'm new to egrep. What pattern could I use to find all lines that match this pattern: <beginning of line><any amount of whitespace>sub<space>. I want it to return the entire line.
(I'm trying to generate a list of all Perl sub definitions in a list of Perl modules.)
Thanks for your help! (7 Replies)
Hi
I need to look for the range dates of access_log for example:
between 02/May/2009:14:56:20 and 05/May/2009:18:46:06
then write the content to another file. Date and time is very important for me to concatenate them into access_log later.
Thanks (2 Replies)
Hi
I use arp to get the mac-addresses of my hosts.
# arp -a | grep 192.168.0.
e1000g0 192.168.0.1 255.255.255.255 o 00:00:00:00:00:01
e1000g0 192.168.0.11 255.255.255.255 o 00:00:00:00:00:02
e1000g0 192.168.0.2 255.255.255.255 ... (12 Replies)
Hi everyone
i want to write a script to grep multiple pattern from all the file from a dir.
for example I want to get all the record number from XML file who's last name is asd, smith, dfrt,gokul,and sinha.
I tried
egrep('sinha'|'gokul'|'asd')
but it is not working
also i tried saving... (2 Replies)
Hi All,
Can some one please help me how to grep the comments from "oracle" & "sybase" code. I would like to grep below type of pattern.
--
/* */
Please help. (6 Replies)
Hello all,
after spending hours of searching the web I decided to create an account here. This is my first post and I hope one of the experts can help.
I need to resolve a grep / sed / xargs / awk problem.
My input file is just like this:
----------------------------------... (6 Replies)
Hi all
I need your help to get a high-performance solution.
I am working on a extensive script to automate file restores using the bprestore tool on a Solaris 5.10 server (bash 3.00). I will only paste the needed parts of the script to avoid any confusion.
To use the script the user has to... (2 Replies)
Discussion started by: Anonym
2 Replies
LEARN ABOUT LINUX
posix_fadvise
POSIX_FADVISE(2) Linux Programmer's Manual POSIX_FADVISE(2)NAME
posix_fadvise - predeclare an access pattern for file data
SYNOPSIS
#include <fcntl.h>
int posix_fadvise(int fd, off_t offset, off_t len, int advice);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
posix_fadvise():
_XOPEN_SOURCE >= 600 || _POSIX_C_SOURCE >= 200112L
DESCRIPTION
Programs can use posix_fadvise() to announce an intention to access file data in a specific pattern in the future, thus allowing the kernel
to perform appropriate optimizations.
The advice applies to a (not necessarily existent) region starting at offset and extending for len bytes (or until the end of the file if
len is 0) within the file referred to by fd. The advice is not binding; it merely constitutes an expectation on behalf of the application.
Permissible values for advice include:
POSIX_FADV_NORMAL
Indicates that the application has no advice to give about its access pattern for the specified data. If no advice is given for an
open file, this is the default assumption.
POSIX_FADV_SEQUENTIAL
The application expects to access the specified data sequentially (with lower offsets read before higher ones).
POSIX_FADV_RANDOM
The specified data will be accessed in random order.
POSIX_FADV_NOREUSE
The specified data will be accessed only once.
POSIX_FADV_WILLNEED
The specified data will be accessed in the near future.
POSIX_FADV_DONTNEED
The specified data will not be accessed in the near future.
RETURN VALUE
On success, zero is returned. On error, an error number is returned.
ERRORS
EBADF The fd argument was not a valid file descriptor.
EINVAL An invalid value was specified for advice.
ESPIPE The specified file descriptor refers to a pipe or FIFO. (Linux actually returns EINVAL in this case.)
VERSIONS
posix_fadvise() appeared in kernel 2.5.60. Glibc support has been provided since version 2.2.
CONFORMING TO
POSIX.1-2001. Note that the type of the len argument was changed from size_t to off_t in POSIX.1-2003 TC1.
NOTES
Under Linux, POSIX_FADV_NORMAL sets the readahead window to the default size for the backing device; POSIX_FADV_SEQUENTIAL doubles this
size, and POSIX_FADV_RANDOM disables file readahead entirely. These changes affect the entire file, not just the specified region (but
other open file handles to the same file are unaffected).
POSIX_FADV_WILLNEED initiates a nonblocking read of the specified region into the page cache. The amount of data read may be decreased by
the kernel depending on virtual memory load. (A few megabytes will usually be fully satisfied, and more is rarely useful.)
In kernels before 2.6.18, POSIX_FADV_NOREUSE had the same semantics as POSIX_FADV_WILLNEED. This was probably a bug; since kernel 2.6.18,
this flag is a no-op.
POSIX_FADV_DONTNEED attempts to free cached pages associated with the specified region. This is useful, for example, while streaming large
files. A program may periodically request the kernel to free cached data that has already been used, so that more useful cached pages are
not discarded instead.
Pages that have not yet been written out will be unaffected, so if the application wishes to guarantee that pages will be released, it
should call fsync(2) or fdatasync(2) first.
BUGS
In kernels before 2.6.6, if len was specified as 0, then this was interpreted literally as "zero bytes", rather than as meaning "all bytes
through to the end of the file".
SEE ALSO readahead(2), sync_file_range(2), posix_fallocate(3), posix_madvise(3), feature_test_macros(7)COLOPHON
This page is part of release 3.27 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2010-09-20 POSIX_FADVISE(2)