od - dump files in octal and other formats

NAME

od - dump files in octal and other formats

SYNOPSIS

od [OPTION]... [FILE]...
od --traditional [FILE] [[+]OFFSET [[+]LABEL]]

DESCRIPTION

Write an unambiguous representation, octal bytes by default, of FILE to standard output. With more than one FILE argument, concatenate them in the listed order to form the input. With no FILE, or when FILE is -, read standard input.

All arguments to long options are mandatory for short options.

-A, --address-radix=RADIX

decide how file offsets are printed

-j, --skip-bytes=BYTES

skip BYTES input bytes first

-N, --read-bytes=BYTES

limit dump to BYTES input bytes

-s, --strings[=BYTES]

output strings of at least BYTES graphic chars

-t, --format=TYPE

select output format or formats

-v, --output-duplicates

do not use * to mark line suppression

-w, --width[=BYTES]

output BYTES bytes per output line

--traditional

accept arguments in traditional form

--help

display this help and exit

--version

output version information and exit

Traditional format specifications may be intermixed; they accumulate:

-a

same as -t a, select named characters

-b

same as -t oC, select octal bytes

-c

same as -t c, select ASCII characters or backslash escapes

-d

same as -t u2, select unsigned decimal shorts

-f

same as -t fF, select floats

-h

same as -t x2, select hexadecimal shorts

-i

same as -t d2, select decimal shorts

-l

same as -t d4, select decimal longs

-o

same as -t o2, select octal shorts

-x

same as -t x2, select hexadecimal shorts

For older syntax (second call format), OFFSET means -j OFFSET. LABEL is the pseudo-address at first byte printed, incremented when dump is progressing. For OFFSET and LABEL, a 0x or 0X prefix indicates hexadecimal, suffixes may be . for octal and b for multiply by 512.

TYPE is made up of one or more of these specifications:

a

named character

c

ASCII character or backslash escape

d[SIZE]

signed decimal, SIZE bytes per integer

f[SIZE]

floating point, SIZE bytes per integer

o[SIZE]

octal, SIZE bytes per integer

u[SIZE]

unsigned decimal, SIZE bytes per integer

x[SIZE]

hexadecimal, SIZE bytes per integer

SIZE is a number. For TYPE in doux, SIZE may also be C for sizeof(char), S for sizeof(short), I for sizeof(int) or L for sizeof(long). If TYPE is f, SIZE may also be F for sizeof(float), D for sizeof(double) or L for sizeof(long double).

RADIX is d for decimal, o for octal, x for hexadecimal or n for none. BYTES is hexadecimal with 0x or 0X prefix, it is multiplied by 512 with b suffix, by 1024 with k and by 1048576 with m. Adding a z suffix to any type adds a display of printable characters to the end of each line of output. --string without a number implies 3. --width without a number implies 32. By default, od uses -A o -t d2 -w 16.

Desktop Linux Face-Off: Ubuntu 8.04 vs. Fedora 9

Over the past decade, Linux has emerged from a herd of obscure and nerdy operating systems to warrant a place in even the most technologically unsophisticated business environments. And in the past three years, a few distributions have made stupendous leaps in performance and usability, winning the affection of millions of mainstream desktop users.

The recent releases of Ubuntu 8.04 and Fedora 9--two top Linux distributions--mark another step forward in the evolution of the Linux desktop. I've been running both of them to see which offers the better blend of usability and advanced features.

Ubuntu 8.04 Hardy Heron

Since the release of version 5.10 (aka Breezy Badger) in 2005, Ubuntu Linux has stood apart from hundreds of other Linux distributions, capturing the attention of penguin heads and of users seeking a free, stable, usable alternative to Microsoft Windows. With its click-and-go Live CD installation and its support for a broad base of hardware devices, Ubuntu built a reputation for ease of use that changed the way many people think about Linux. PC World was so impressed that Ubuntu landed on our list of "The 100 Best Products of 2006," a first for any flavor of Linux.

The latest version of Ubuntu, 8.04 (aka Hardy Heron, or just Hardy for short), builds strongly on the foundation laid by its predecessors. This release is a Long Term Support edition, to be supported until April 2011, and Hardy Heron shows more polish and refinement than any other Linux distribution I've seen.

The operating system comes packed with new features, beginning with a revised kernel (2.6.24), the latest version of Xorg (7.3), and the most recent Gnome desktop interface (2.22.1). On top of these advances, Hardy offers several new default applications, including Brasero for CD/DVD burning, the Transmission BitTorrent client, and Vinagre virtual network computing software for remote desktop viewing. You also get support for enhanced security via SELinux (Security-Enhanced Linux)--but in Ubuntu 8.04 it's not installed by default, as it is in Fedora 9.

From the get-go, the Hardy Heron experience is smooth. I installed it on several machines, including an aging laptop with a Via graphics controller that's notorious for making a hash of things in Linux. Each installation found and recognized all of my hardware without requiring a reboot. Even my media card slot, which Windows can never locate a driver for on its own, worked right off the bat. Existing Ubuntu users enjoy even slicker installation: The Hardy Heron upgrade comes through the Update Manager, and one click initiates a totally automated --albeit fairly long--upgrade process that leaves all of the user's data in place.

Ubuntu's automated Hardware Drivers utility seeks out proprietary drivers for devices in your system, simplifying the task of grabbing the latest proprietary nVidia driver, for instance, so that you can enable Desktop Effects. Some hard-core open-source advocates disapprove of Ubuntu's compromise with the closed-source world, but end users who care more about usability than ideology will find this arrangement a boon.

Apart from the new default apps, Ubuntu hasn't changed much in overall look and feel this time around. Sure, there's artsy heron-themed wallpaper, but longtime Ubuntu desktop users will find little else to poke at in this version. That development indicates that Ubuntu has matured to the point where it can focus on refining its feature set rather than massively reworking its elements in each new version.

The changes in the default apps seem judicious rather than sweeping. Brasero, for instance, is a far more complete disc-burning utility than Serpentine, the relatively simple CD burner found in previous versions of Ubuntu.

Hardy Heron still lacks a few features that I had hoped to see as defaults by now, such as a Desktop Effects Manager for Gnome. Downloading Compiz Configuration Settings Manager through apt-get (the command-line tool for handling packages) isn't hard, but it should really be there in the first place. Without it, newbies have no idea how to turn on the desktop cube they've heard so much about. Also still absent is a decent theme manager to take advantage of Desktop Effects.

Minor quibbles aside, Ubuntu 8.04 is the best-assembled and most polished Linux distribution I've ever used. Ubuntu 8.04 performs well where Windows XP and Vista screech to a halt, particularly on older hardware. And since it comes with OpenOffice.org, Firefox, Evolution Mail, and a host of other apps right out of the box, it may be the best way to breathe new life into a seemingly moribund PC.

Fedora 9

Fedora was born as an all-open-source alternative to the business-centric Red Hat Linux. As such, it enjoys a solid legacy of Linux development. Unfortunately, as the nonprofit cousin of a major commercial distribution, Fedora doesn't always seem to get the attention it deserves. But last year, Fedora doffed the shadow of rival Ubuntu by releasing of Fedora 8, which offered a simple, graphical installer and the best hardware support we'd seen from the Fedora distribution. Nevertheless, it lagged behind Ubuntu in ease of installation and overall usability--largely because its commitment to Free and Open Source Software (FOSS) left it without complete drivers for some major hardware, including nVidia and ATI cards and various wireless cards. Any astute Linux user could add these, certainly, but the process was too geeky for average Joes who just wanted to give Linux a try.

With version 9, Fedora has stepped up its ease-of-use game. Gnome 2.22 brings a host of great new features, including support for Webcam videos. A prerelease version of Xorg 7.4, however, causes problems with nVidia cards, preventing Desktop Effects--which is now standard in Fedora 9--from working. At posting time, this problem remained unresolved, though contributors to the Fedora Forums suggested that it would soon be corrected. Fedora 9 also has a newer kernel (2.6.25) than Ubuntu 8.04.

One of the most important changes in the new Fedora is immediately visible: its Anaconda installer can dynamically resize NTFS hard-drive partitions, making the task of adding Fedora to existing Windows installations much easier. Ubuntu users have long enjoyed a similar feature, so it's nice to see Fedora catch up. Another new feature of the installer is a one-click option for drive encryption. Overall, Fedora's revamped install routine is the distribution's best yet, and it nearly matches Ubuntu's in simplicity and ease of use.

I liked Fedora 9's new PackageKit, a graphical interface for Fedora's Yum update utility, too. PackageKit is the nicest update manager I've tried in Linux, with big, friendly icons for bug fixes and security updates. Also, like Ubuntu 8.04, Fedora 9 now uses PulseAudio to control sound devices throughout the OS.

By default, Fedora includes SELinux, which enforces security policies throughout the OS. Developed by the U.S. National Security Agency, this app does an excellent job of alerting users to potential security threats and managing user authentication. Most users will find that the biggest benefit of SELinux is its management of root user authority: The program alerts you when you've had root privileges activated for more than a few minutes, so you can minimize your exposure from this vulnerability.

For users who are already familiar with Linux, Fedora 9 is an excellent choice. Robust security features and installation options make it somewhat more versatile than Ubuntu, which offers a more streamlined (and therefore more restricted) installation. For most users, though, including millions interested in trying Linux for the first time, Fedora lacks the polish and ready-to-run simplicity of its more popular rival.

Ubuntu 8.0.4 offers a level of functionality comparable to that of Mac OS and Windows, from delivery to installation to daily use. Unfortunately, the ties that bind all Linux distributions--primarily a lack of support for major Windows- and Mac-based business, design, and gaming applications--still hold Ubuntu back from mass popularity. For users with such moderate computing needs as Web browsing, e-mail, and basic document creation, however, Hardy is a compelling option.

Ubuntu 8.04

The best all-around Linux distribution available today.
Free
Ubuntu's Web site

Fedora 9

An excellent choice for experienced Linux users.
Free
Fedora's Web site

STOPPED JOBS and job control...

When you try to exit a window or logout, you may get a message:

 There are stopped jobs.

This means that a program you were running has been suspended (usually by
typing Ctrl-Z) and has not been properly terminated.  If you just try to exit
again, the system will automatically terminate those jobs.  If you want to see
what those jobs are, use the 'jobs' command.  Just type:

 jobs

You will see a listing, which may look like this:

 [1]  - Stopped  foo
 [2]  + Stopped  bar

If you want to continue using one of the jobs in the list, use the 'fg'
command.  For example, if you wanted to continue using 'foo' in the above
listing, type this:

 fg %1

Actually, the 'fg' part is optional.  So, you could just type:

 %1

...and get the same effect.  If instead you want to just terminate a job, use
the 'kill' command.  For example, if you wanted to kill 'bar' in the above
listing, type this:

 kill %2

The information below describes jobs in much more detail, if you're
interested.

The shell associates a job with each pipeline (most often a single
command/program) It keeps a table of current jobs, printed by the "jobs"
command, and assigns them small integer numbers.  When a job is started
asynchronously with '&' (started in the background), the shell prints a line
which looks like:

 [1] 1234

indicating that the job that was started asynchronously was job number 1 and
had one (top-level) process, whose process ID number was 1234.

If you are running a job and wish to do something else, you may type Ctrl-Z,
which sends a STOP signal to the current job.  The shell will then normally
indicate that the job has been 'Stopped', and print another prompt.  You can
then manipulate the state of this job, putting it in the background with the
'bg' command, or run some other commands and then eventually bring the job
back into the foreground with the foreground command 'fg'.  A Ctrl-Z takes
effect immediately and is like an interrupt in that pending output and unread
input are discarded when it is typed.  There is another special key, Ctrl-Y,
which does not generate a STOP signal until a program attempts to read(2) it.
This can be typed ahead when you have prepared some commands for a job which
you wish to stop after it has read them.

A job being run in the background will stop if it tries to read from the
terminal.  Background jobs are normally allowed to produce output, but this
can be disabled by giving the command 'stty tostop'.  If you set this tty
option, then background jobs will stop when they try to produce output like
they do when they try to read input.

There are several ways to refer to jobs in the shell.  The character '%'
introduces a job name.  If you wish to refer to job number 1, you can name it
as '%1'.  Just naming a job brings it to the foreground; thus '%1' is a
synonym for 'fg %1', bringing job 1 back into the foreground.  Similarly
saying '%1 &' resumes job 1 in the background.  Jobs can also be named by
prefixes of the string typed in to start them, if these prefixes are
unambiguous, thus '%ex' would normally restart a suspended ex(1) job, if there
were only one suspended job whose name began with the string 'ex'.  It is also
possible to say '%?string' which specifies a job whose text contains string,
if there is only one such job.

The shell maintains a notion of the current and previous jobs.  In output
pertaining to jobs, the current job is marked with a '+' and the previous job
with a '-'.  The abbreviation '%+' refers to the current job and '%-' refers
to the previous job.  For close analogy with the syntax of the history
mechanism, '%%' is also a synonym for the current job.

cron job details...

To see all the Cron jobs aunder one user use command ..
>>> crontab -l

To add a new Cron job for a user u can use the command...
>>>> crontab -e

While adding one job to the crontab u have to follow following format...

Syntax of crontab

Your cron job looks like as follows:
1 2 3 4 5 /path/to/command arg1 arg2

Where,

• 1: Minute (0-59)
• 2: Hours (0-23)
• 3: Day (0-31)
• 4: Month (0-12 [12 == December])
• 5: Day of the week(0-7 [7 or 0 == sunday])
• /path/to/command - Script or command name to schedule

Same above five fields structure can be easily remembered with following diagram:

* * * * * command to be executed
- - - - -
| | | | |
| | | | ----- Day of week (0 - 7) (Sunday=0 or 7)
| | | ------- Month (1 - 12)
| | --------- Day of month (1 - 31)
| ----------- Hour (0 - 23)
------------- Minute (0 - 59)

Use of operators

An operator allows you to specifying multiple values in a field. There are three operators:

1. The asterisk (*) : This operator specifies all possible values for a field. For example, an asterisk in the hour time field would be equivalent to every hour or an asterisk in the month field would be equivalent to every month.
2. The comma (,) : This operator specifies a list of values, for example: "1,5,10,15,20, 25".
3. The dash (-) : This operator specifies a range of values, for example: "5-15" days , which is equivalent to typing "5,6,7,8,9,....,13,14,15" using the comma operator.

one example :
55 00 * * * env OMC_TOP=/usr/omc /usr/omc/sbin/maintain_script -r -d 7 /usr/omc/logs gpomcaudit\* #MOMC42 parser audit files +7 days

Handling of signals in Shell scripting..

trap [-lp] [arg] [sigspec ...]

The command arg is to be read and executed when the shell receives signal(s) sigspec। If arg is absent or -, all specified signals are reset to their original values (the values they had upon entrance to the shell)।
If arg is the null string the signal specified by each sigspec is ignored by the shell and by the commands it invokes।
If arg is not present and -p has been supplied, then the trap commands associated with each sigspec are displayed।
If no arguments are supplied or if only -p is given, trap prints the list of commands associated with each signal number।
Each sigspec is either a signal name defined in <signal.h>, or a signal number।
If a sigspec is EXIT (0) the command arg is executed on exit from the shell। If a
sigspec is DEBUG, the command arg is executed after every simple command (see SHELL GRAMMAR above)।
If a sigspec is ERR, the command arg is executed whenever a simple command has a non-zero exit status।
The ERR trap is not executed if the failed command is part of an until or while loop, part of an if statement, part of a && or || list, or if the command's return value is being inverted via !. The -l option causes the shell to print a list of signal names and their corresponding numbers। Signals ignored upon entry to the shell cannot be trapped or reset। Trapped signals are reset to their original values in a child process when it is created। The return status is false if any sigspec is invalid; otherwise trap returns true.

To Take Backup of Files in Linux/+

cpio - copy files to and from archives

cpio {-o|--create} [-0acvABLV] [-C bytes] [-H format] [-M message] [-O [[user@]host:]archive] [-F [[user@]host:]archive] [--file=[[user@]host:]archive] [--format=format] [--message=message] [--null] [--reset-access-time] [--verbose] [--dot] [--append] [--block-size=blocks] [--dereference] [--io-size=bytes] [--quiet] [--force-local] [--rsh-command=command] [--help] [--version] <> archive]

cpio {-i|--extract} [-bcdfmnrtsuvBSV] [-C bytes] [-E file] [-H format] [-M message] [-R [user][:.][group]] [-I [[user@]host:]archive] [-F [[user@]host:]archive] [--file=[[user@]host:]archive] [--make-directories] [--nonmatching] [--preserve-modification-time] [--numeric-uid-gid] [--rename] [-t|--list] [--swap-bytes] [--swap] [--dot] [--unconditional] [--verbose] [--block-size=blocks] [--swap-halfwords] [--io-size=bytes] [--pattern-file=file] [--format=format] [--owner=[user][:.][group]] [--no-preserve-owner] [--message=message] [--force-local] [--no-absolute-filenames] [--sparse] [--only-verify-crc] [--quiet] [--rsh-command=command] [--help] [--version] [pattern...] [< archive]

cpio {-p|--pass-through} [-0adlmuvLV] [-R [user][:.][group]] [--null] [--reset-access-time] [--make-directories] [--link] [--quiet] [--preserve-modification-time] [--unconditional] [--verbose] [--dot] [--dereference] [--owner=[user][:.][group]] [--no-preserve-owner] [--sparse] [--help] [--version] destination-directory < name-list


cpio copies files into or out of a cpio or tar archive, which is a file that contains other files plus information about them, such as their file name, owner, timestamps, and access permissions. The archive can be another file on the disk, a magnetic tape, or a pipe. cpio has three operating modes.

In copy-out mode, cpio copies files into an archive. It reads a list of filenames, one per line, on the standard input, and writes the archive onto the standard output. A typical way to generate the list of filenames is with the find command; you should give find the -depth option to minimize problems with permissions on directories that are unwritable or not searchable.

In copy-in mode, cpio copies files out of an archive or lists the archive contents. It reads the archive from the standard input. Any non-option command line arguments are shell globbing patterns; only files in the archive whose names match one or more of those patterns are copied from the archive. Unlike in the shell, an initial `.' in a filename does match a wildcard at the start of a pattern, and a `/' in a filename can match wildcards. If no patterns are given, all files are extracted.

In copy-pass mode, cpio copies files from one directory tree to another, combining the copy-out and copy-in steps without actually using an archive. It reads the list of files to copy from the standard input; the directory into which it will copy them is given as a non-option argument.

cpio supports the following archive formats: binary, old ASCII, new ASCII, crc, HPUX binary, HPUX old ASCII, old tar, and POSIX.1 tar. The binary format is obsolete because it encodes information about the files in a way that is not portable between different machine architectures. The old ASCII format is portable between different machine architectures, but should not be used on file systems with more than 65536 i-nodes. The new ASCII format is portable between different machine architectures and can be used on any size file system, but is not supported by all versions of cpio; currently, it is only supported by GNU and Unix System V R4. The crc format is like the new ASCII format, but also contains a checksum for each file which cpio calculates when creating an archive and verifies when the file is extracted from the archive. The HPUX formats are provided for compatibility with HPUX's cpio which stores device files differently.

The tar format is provided for compatability with the tar program. It can not be used to archive files with names longer than 100 characters, and can not be used to archive "special" (block or character devices) files. The POSIX.1 tar format can not be used to archive files with names longer than 255 characters (less unless they have a "/" in just the right place).

By default, cpio creates binary format archives, for compatibility with older cpio programs. When extracting from archives, cpio automatically recognizes which kind of archive it is reading and can read archives created on machines with a different byte-order.

OPTIONS

-0, --null
In copy-out and copy-pass modes, read a list of filenames terminated by a null character instead of a newline, so that files whose names contain newlines can be archived. GNU find is one way to produce a list of null-terminated filenames.
-a, --reset-access-time
Reset the access times of files after reading them, so that it does not look like they have just been read.
-A, --append
Append to an existing archive. Only works in copy-out mode. The archive must be a disk file specified with the -O or -F (--file) option.
-b, --swap
In copy-in mode, swap both halfwords of words and bytes of halfwords in the data. Equivalent to -sS. Use this option to convert 32-bit integers between big-endian and little-endian machines.
-B
Set the I/O block size to 5120 bytes. Initially the block size is 512 bytes.
--block-size=BLOCK-SIZE
Set the I/O block size to BLOCK-SIZE * 512 bytes.
-c
Identical to "-H newc", use the new (SVR4) portable format. If you wish the old portable (ASCII) archive format, use "-H odc" instead.
-C IO-SIZE, --io-size=IO-SIZE
Set the I/O block size to IO-SIZE bytes.
-d, --make-directories
Create leading directories where needed.
-E FILE, --pattern-file=FILE
In copy-in mode, read additional patterns specifying filenames to extract or list from FILE. The lines of FILE are treated as if they had been non-option arguments to cpio.
-f, --nonmatching
Only copy files that do not match any of the given patterns.
-F, --file=archive
Archive filename to use instead of standard input or output. To use a tape drive on another machine as the archive, use a filename that starts with `HOSTNAME:'. The hostname can be preceded by a username and an `@' to access the remote tape drive as that user, if you have permission to do so (typically an entry in that user's `~/.rhosts' file).
--force-local
With -F, -I, or -O, take the archive file name to be a local file even if it contains a colon, which would ordinarily indicate a remote host name.
-H FORMAT, --format=FORMAT
Use archive format FORMAT. The valid formats are listed below; the same names are also recognized in all-caps. The default in copy-in mode is to automatically detect the archive format, and in copy-out mode is "bin".

bin
The obsolete binary format.
odc
The old (POSIX.1) portable format.
newc
The new (SVR4) portable format, which supports file systems having more than 65536 i-nodes.
crc
The new (SVR4) portable format with a checksum added.
tar
The old tar format.
ustar
The POSIX.1 tar format. Also recognizes GNU tar archives, which are similar but not identical.
hpbin
The obsolete binary format used by HPUX's cpio (which stores device files differently).
hpodc
The portable format used by HPUX's cpio (which stores device files differently).

-i, --extract
Run in copy-in mode.
-I archive
Archive filename to use instead of standard input. To use a tape drive on another machine as the archive, use a filename that starts with `HOSTNAME:'. The hostname can be preceded by a username and an `@' to access the remote tape drive as that user, if you have permission to do so (typically an entry in that user's `~/.rhosts' file).
-k
Ignored; for compatibility with other versions of cpio.
-l, --link
Link files instead of copying them, when possible.
-L, --dereference
Dereference symbolic links (copy the files that they point to instead of copying the links).
-m, --preserve-modification-time
Retain previous file modification times when creating files.
-M MESSAGE, --message=MESSAGE
Print MESSAGE when the end of a volume of the backup media (such as a tape or a floppy disk) is reached, to prompt the user to insert a new volume. If MESSAGE contains the string "%d", it is replaced by the current volume number (starting at 1).
-n, --numeric-uid-gid
In the verbose table of contents listing, show numeric UID and GID instead of translating them into names. Also extracts tar archives using the numeric UID and GID instead of the user/group names. (cpio archives are always extracted using the numeric UID and GID.)
--no-absolute-filenames
In copy-in mode, create all files relative to the current directory, even if they have an absolute file name in the archive.
--no-preserve-owner
In copy-in mode and copy-pass mode, do not change the ownership of the files; leave them owned by the user extracting them. This is the default for non-root users, so that users on System V don't inadvertantly give away files.
-o, --create
Run in copy-out mode.
-O archive
Archive filename to use instead of standard output. To use a tape drive on another machine as the archive, use a filename that starts with `HOSTNAME:'. The hostname can be preceded by a username and an `@' to access the remote tape drive as that user, if you have permission to do so (typically an entry in that user's `~/.rhosts' file).
--only-verify-crc
When reading a CRC format archive in copy-in mode, only verify the CRC's of each file in the archive, don't actually extract the files.
-p, --pass-through
Run in copy-pass mode.
--quiet
Do not print the number of blocks copied.
-r, --rename
Interactively rename files.
-R [user][:.][group], --owner [user][:.][group]
In copy-out and copy-pass modes, set the ownership of all files created to the specified user and/or group. Either the user or the group, or both, must be present. If the group is omitted but the ":" or "." separator is given, use the given user's login group. Only the super-user can change files' ownership.
--rsh-command=COMMAND
Notifies mt that it should use COMMAND to communicate with remote devices instead of /usr/bin/ssh or /usr/bin/rsh.
--sparse
In copy-in and copy-pass modes, write files with large blocks of zeros as sparse files.
-s, --swap-bytes
In copy-in mode, swap the bytes of each halfword (pair of bytes) in the files.
-S, --swap-halfwords
In copy-in mode, swap the halfwords of each word (4 bytes) in the files.
-t, --list
Print a table of contents of the input.
-u, --unconditional
Replace all files, without asking whether to replace existing newer files with older files.
-v, --verbose
List the files processed, or with -t, give an `ls -l' style table of contents listing. In a verbose table of contents of a ustar archive, user and group names in the archive that do not exist on the local system are replaced by the names that correspond locally to the numeric UID and GID stored in the archive.
-V --dot
Print a "." for each file processed.
--version
Print the cpio program version number and exit.

stat() function

stat, fstat, lstat - get file status

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

int stat(const char *path, struct stat *buf);
int fstat(int filedes, struct stat *buf);
int lstat(const char *path, struct stat *buf);

Description

These functions return information about a file. No permissions are required on the file itself, but -- in the case of stat() and lstat() -- execute (search) permission is required on all of the directories in path that lead to the file.

stat() stats the file pointed to by path and fills in buf.

lstat() is identical to stat(), except that if path is a symbolic link, then the link itself is stat-ed, not the file that it refers to.

fstat() is identical to stat(), except that the file to be stat-ed is specified by the file descriptor filedes.

All of these system calls return a stat structure, which contains the following fields:

struct stat {
   dev_t     st_dev;     /* ID of device containing file */
   ino_t     st_ino;     /* inode number */
   mode_t    st_mode;    /* protection */
   nlink_t   st_nlink;   /* number of hard links */
   uid_t     st_uid;     /* user ID of owner */
   gid_t     st_gid;     /* group ID of owner */
   dev_t     st_rdev;    /* device ID (if special file) */
   off_t     st_size;    /* total size, in bytes */
   blksize_t st_blksize; /* blocksize for filesystem I/O */
   blkcnt_t  st_blocks;  /* number of blocks allocated */
   time_t    st_atime;   /* time of last access */
   time_t    st_mtime;   /* time of last modification */
   time_t    st_ctime;   /* time of last status change */
};

The following flags are defined for the st_mode field:

S_IFMT	0170000	bitmask for the file type bitfields
S_IFSOCK	0140000	socket
S_IFLNK	0120000	symbolic link
S_IFREG	0100000	regular file
S_IFBLK	0060000	block device
S_IFDIR	0040000	directory
S_IFCHR	0020000	character device
S_IFIFO	0010000	FIFO
S_ISUID	0004000	set UID bit
S_ISGID	0002000	set-group-ID bit (see below)
S_ISVTX	0001000	sticky bit (see below)
S_IRWXU	00700	mask for file owner permissions
S_IRUSR	00400	owner has read permission
S_IWUSR	00200	owner has write permission
S_IXUSR	00100	owner has execute permission
S_IRWXG	00070	mask for group permissions
S_IRGRP	00040	group has read permission
S_IWGRP	00020	group has write permission
S_IXGRP	00010	group has execute permission
S_IRWXO	00007	mask for permissions for others (not in group)
S_IROTH	00004	others have read permission
S_IWOTH	00002	others have write permission
S_IXOTH	00001	others have execute permission

Linux Notes

Since kernel 2.5.48, the stat structure supports nanosecond resolution for the three file timestamp fields. Glibc exposes the nanosecond component of each field using names either of the form st_atim.tv_nsec, if the _BSD_SOURCE or _SVID_SOURCE feature test macro is defined, or of the form st_atimensec, if neither of these macros is defined. On file systems that do not support sub-second timestamps, these nanosecond fields are returned with the value 0.

For most files under the /proc directory, stat() does not return the file size in the st_size field; instead the field is returned with the value 0.

Return Value

On success, zero is returned. On error, -1 is returned, and errno is set appropriately.

Linux CLI commands

Command		Description
•	apropos whatis	Show commands pertinent to string. See also threadsafe
•	man -t man | ps2pdf - > man.pdf	make a pdf of a manual page
	which command	Show full path name of command
	time command	See how long a command takes
•	time cat	Start stopwatch. Ctrl-d to stop. See also sw
•	nice info	Run a low priority command (The "info" reader in this case)
•	renice 19 -p $$	Make shell (script) low priority. Use for non interactive tasks
dir navigation
•	cd -	Go to previous directory
•	cd	Go to $HOME directory
	(cd dir && command)	Go to dir, execute command and return to current dir
•	pushd .	Put current dir on stack so you can popd back to it
file searching
•	alias l='ls -l --color=auto'	quick dir listing
•	ls -lrt	List files by date. See also newest and find_mm_yyyy
•	ls /usr/bin | pr -T9 -W$COLUMNS	Print in 9 columns to width of terminal
	find -name '*.[ch]' | xargs grep -E 'expr'	Search 'expr' in this dir and below. See also findrepo
	find -type f -print0 | xargs -r0 grep -F 'example'	Search all regular files for 'example' in this dir and below
	find -maxdepth 1 -type f | xargs grep -F 'example'	Search all regular files for 'example' in this dir
	find -maxdepth 1 -type d | while read dir; do echo $dir; echo cmd2; done	Process each item with multiple commands (in while loop)
•	find -type f ! -perm -444	Find files not readable by all (useful for web site)
•	find -type d ! -perm -111	Find dirs not accessible by all (useful for web site)
•	locate -r 'file[^/]*\.txt'	Search cached index for names. This re is like glob *file*.txt
•	look reference	Quickly search (sorted) dictionary for prefix
•	grep --color reference /usr/share/dict/words	Highlight occurances of regular expression in dictionary
archives and compression
	gpg -c file	Encrypt file
	gpg file.gpg	Decrypt file
	tar -c dir/ | bzip2 > dir.tar.bz2	Make compressed archive of dir/
	bzip2 -dc dir.tar.bz2 | tar -x	Extract archive (use gzip instead of bzip2 for tar.gz files)
	tar -c dir/ | gzip | gpg -c | ssh user@remote 'dd of=dir.tar.gz.gpg'	Make encrypted archive of dir/ on remote machine
	find dir/ -name '*.txt' | tar -c --files-from=- | bzip2 > dir_txt.tar.bz2	Make archive of subset of dir/ and below
	find dir/ -name '*.txt' | xargs cp -a --target-directory=dir_txt/ --parents	Make copy of subset of dir/ and below
	( tar -c /dir/to/copy ) | ( cd /where/to/ && tar -x -p )	Copy (with permissions) copy/ dir to /where/to/ dir
	( cd /dir/to/copy && tar -c . ) | ( cd /where/to/ && tar -x -p )	Copy (with permissions) contents of copy/ dir to /where/to/
	( tar -c /dir/to/copy ) | ssh -C user@remote 'cd /where/to/ && tar -x -p'	Copy (with permissions) copy/ dir to remote:/where/to/ dir
	dd bs=1M if=/dev/sda | gzip | ssh user@remote 'dd of=sda.gz'	Backup harddisk to remote machine
rsync (Use the --dry-run option for testing)
	rsync -P rsync://rsync.server.com/path/to/file file	Only get diffs. Do multiple times for troublesome downloads
	rsync --bwlimit=1000 fromfile tofile	Locally copy with rate limit. It's like nice for I/O
	rsync -az -e ssh --delete ~/public_html/ remote.com:'~/public_html'	Mirror web site (using compression and encryption)
	rsync -auz -e ssh remote:/dir/ . && rsync -auz -e ssh . remote:/dir/	Synchronize current directory with remote one
ssh (Secure SHell)
	ssh $USER@$HOST command	Run command on $HOST as $USER (default command=shell)
•	ssh -f -Y $USER@$HOSTNAME xeyes	Run GUI command on $HOSTNAME as $USER
	scp -p -r $USER@$HOST: file dir/	Copy with permissions to $USER's home directory on $HOST
	ssh -g -L 8080:localhost:80 root@$HOST	Forward connections to $HOSTNAME:8080 out to $HOST:80
	ssh -R 1434:imap:143 root@$HOST	Forward connections from $HOST:1434 in to imap:143
wget (multi purpose download tool)
•	(cd cli && wget -nd -pHEKk http://www.pixelbeat.org/cmdline.html)	Store local browsable version of a page to the current dir
	wget -c http://www.example.com/large.file	Continue downloading a partially downloaded file
	wget -r -nd -np -l1 -A '*.jpg' http://www.example.com/dir/	Download a set of files to the current directory
	wget ftp://remote/file[1-9].iso/	FTP supports globbing directly
•	wget -q -O- http://www.pixelbeat.org/timeline.html | grep 'a href' | head	Process output directly
	echo 'wget url' | at 01:00	Download url at 1AM to current dir
	wget --limit-rate=20k url	Do a low priority download (limit to 20KB/s in this case)
	wget -nv --spider --force-html -i bookmarks.html	Check links in a file
	wget --mirror http://www.example.com/	Efficiently update a local copy of a site (handy from cron)
networking (Note ifconfig, route, mii-tool, nslookup commands are obsolete)
	ethtool eth0	Show status of ethernet interface eth0
	ethtool --change eth0 autoneg off speed 100 duplex full	Manually set ethernet interface speed
	iwconfig eth1	Show status of wireless interface eth1
	iwconfig eth1 rate 1Mb/s fixed	Manually set wireless interface speed
•	iwlist scan	List wireless networks in range
•	ip link show	List network interfaces
	ip link set dev eth0 name wan	Rename interface eth0 to wan
	ip link set dev eth0 up	Bring interface eth0 up (or down)
•	ip addr show	List addresses for interfaces
	ip addr add 1.2.3.4/24 brd + dev eth0	Add (or del) ip and mask (255.255.255.0)
•	ip route show	List routing table
	ip route add default via 1.2.3.254	Set default gateway to 1.2.3.254
•	tc qdisc add dev lo root handle 1:0 netem delay 20msec	Add 20ms latency to loopback device (for testing)
•	tc qdisc del dev lo root	Remove latency added above
•	host pixelbeat.org	Lookup DNS ip address for name or vice versa
•	hostname -i	Lookup local ip address (equivalent to host `hostname`)
•	whois pixelbeat.org	Lookup whois info for hostname or ip address
•	netstat -tupl	List internet services on a system
•	netstat -tup	List active connections to/from system
windows networking (Note samba is the package that provides all this windows specific networking support)
•	smbtree	Find windows machines. See also findsmb
	nmblookup -A 1.2.3.4	Find the windows (netbios) name associated with ip address
	smbclient -L windows_box	List shares on windows machine or samba server
	mount -t smbfs -o fmask=666,guest //windows_box/share /mnt/share	Mount a windows share
	echo 'message' | smbclient -M windows_box	Send popup to windows machine (off by default in XP sp2)
text manipulation (Note sed uses stdin and stdout, so if you want to edit files, append newfile)
	sed 's/string1/string2/g'	Replace string1 with string2
	sed 's/\(.*\)1/\12/g'	Modify anystring1 to anystring2
	sed '/ *#/d; /^ *$/d'	Remove comments and blank lines
	sed ':a; /\\$/N; s/\\\n//; ta'	Concatenate lines with trailing \
	sed 's/[ \t]*$//'	Remove trailing spaces from lines
	sed 's/\([\\`\\"$\\\\]\)/\\\1/g'	Escape shell metacharacters active within double quotes
•	seq 10 | sed "s/^/ /; s/ *\(.\{7,\}\)/\1/"	Right align numbers
	sed -n '1000p;1000q'	Print 1000th line
	sed -n '10,20p;20q'	Print lines 10 to 20
	sed -n 's/.*