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Full Discussion: Reg: Query in sed
Top Forums UNIX for Dummies Questions & Answers Reg: Query in sed Post 302203960 by vino on Tuesday 10th of June 2008 08:52:13 AM
Old 06-10-2008
Quote:
Originally Posted by patelamit009
Hi Penchal,


I would appreciate if you can provide me a brief explanation on what you are trying to do in the commnad below.


echo "6-9-2008" | sed 's/\(.\)-\(.\)-\(.*\)/\3-0\2-0\1/g'

Thanks
Amit
The input "6-9-2008" gets converted to "2008-09-06". Here is how it happens.

The sed statement takes the form 's/pattern/replacement/flags'

Here pattern is \(.\)-\(.\)-\(.*\)
replacement is \3-0\2-0\1
and flags is g

In the sed world, a . refers to any character. A .* refers to a collection of characters.
When you do \(.\), you are collecting a single character into a buffer. Hence \(.\)-\(.\)-\(.*\) will put 6 into the first buffer, 9 into the second and 2008 into the third.
Each of these buffers can be accessed within the replacement space by using the notation \1 for the first buffer, \2 for the second and so on and so forth.
When you do \3-0\2-0\1 in the replacement space, you create an output as 2008-09-06.
The 'g' flag tells sed to make the change global i.e. if there are more occurrences, all of them should be considered and changed.
 

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LEARN ABOUT REDHAT

nwbpset

NWBPSET(1)							      nwbpset								NWBPSET(1)

NAME

       nwbpset - Create a bindery property or set its value

SYNOPSIS

       nwbpset [ -h ] [ -S server ] [ -U user name ] [ -P password | -n ] [ -C ]

DESCRIPTION

       nwbpset Reads a property specification from the standard input and creates and sets the corresponding property. The format is determined by
       the output of 'nwbpvalues -c'. nwbpset will hopefully become an important part of the bindery management suite of ncpfs, together with

       As another example, look at the following command line:

	 nwbpvalues -t 1 -o supervisor -p user_defaults -c |
	 sed '2s/.*/ME/'|
	 sed '3s/.*/LOGIN_CONTROL/'|
	 nwbpset

       With this command, the property user_defaults of the user object 'supervisor' is copied into the property login_control of the user  object
       'me'.

	 nwbpvalues -t 1 -o me -p login_control -c |
	 sed '9s/.*/ff/'|
	 nwbpset

       This command disables the user object me.

       Feel free to contribute other examples!

       nwbpset looks up the file $HOME/.nwclient to find a file server, a user name and possibly a password. See nwclient(5) for more information.
       Please note that the access permissions of $HOME/.nwclient MUST be 600 for security reasons.

OPTIONS

       -h
	  -h is used to print out a short help text.

       -S server
	  server is the name of the server you want to use.

       -U user
	  user is the user name to use for login.

       -P password
	  password is the password to use for login. If neither -n nor -P are given, and the user has no open connection to  the  server,  nwbpset
	  prompts for a password.

       -n
	  -n should be given if no password is required for the login.

       -C
	  By default, passwords are converted to uppercase before they are sent to the server, because most servers require this. You can turn off
	  this conversion by -C.

AUTHORS

       nwbpset was written by Volker Lendecke. See the Changes file of ncpfs for other contributors.

nwbpset 							     8/7/1996								NWBPSET(1)
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