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Full Discussion: Help with sed command - find a string between two characters
Top Forums Shell Programming and Scripting Help with sed command - find a string between two characters Post 302715071 by bakunin on Saturday 13th of October 2012 05:49:10 PM
Old 10-13-2012
You might want to know what you did wrong to arrive at something different as expected:

Matches in "sed" are always "greedy". That means of different possible matches always the longest possible is taken. That means:

Code:
$ cat input
xxx [abc] yyy [def] zzz

$ sed -n 's/.*\[//;s/\].*//p' input
def

because /.*\[/ has two possibilities to match something: xxx [ and xxx [abc] yyy [. Of these two options it will always take the second one, never the first one. The second rule s/\].*//p will therefore only get def] zzz" to see, from which it cuts ] zzz.

Seasoned crafters of regexps write therefore, instead of ".*[", "[^[]*[". This is a "negated character class", meaning anything other than a "[", followed by a "[". This expression will always be matched by the nearest anchor character.

I hope this helps.

bakunin
This User Gave Thanks to bakunin For This Post:
vivek_damodaran
 

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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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