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Full Discussion: Need help writing a small script
Top Forums Shell Programming and Scripting Need help writing a small script Post 302204823 by mschwage on Thursday 12th of June 2008 03:06:36 PM
Old 06-12-2008
Quote:
Originally Posted by llsmr777
thank you for the reply!

can you expand on this? please bear with me I'm just learning:

grep -q "2007"; if [ $? -eq 0 ];

-q is option for what again?

[ $? -eq 0 ]; what does this break down to?
The man pages are your friends. Try
Code:
man grep

Specifically, in this case it means to be quiet. No output will be produced- the default is to print to the screen what grep finds. In your case, you don't want to see what it found, you just want to know what it found, and report it. The -q option is perfect for that.

Regardless, grep exits with a code. If it finds something, it exits with code 0 (which perhaps paradoxically means "success" in UNIX shell-land). That number is put into the "$?" variable. Also, the [ is the shell command "test". So
Code:
[ $? -eq 0 ]

means "Test the $? variable and see if it's equal to 0". If so, the test command will exit with code 0 (success). The "if" command checks the exit code of the command it is given- in this instance, the "test" command. So if the test is successful, then do the "then" clause.
-mschwage
 

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LEARN ABOUT OPENSOLARIS

script

script(1)							   User Commands							 script(1)

NAME

       script - make record of a terminal session

SYNOPSIS

       script [-a] [filename]

DESCRIPTION

       The  script  utility  makes a record of everything printed on your screen. The record is written to filename. If no file name is given, the
       record is saved in the file typescript. See WARNINGS.

       The script command forks and creates a sub-shell, according to the value of $SHELL, and records the text from this session. The script ends
       when the forked shell exits or when Control-d is typed.

OPTIONS

       The following option is supported:

       -a    Appends the session record to filename, rather than overwriting it.

NOTES

       script places everything that appears on the screen in filename, including prompts.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+
       |CSI			     |Enabled			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       attributes(5)

WARNINGS

       script  can  pose  a  security risk when used in directories that are writable by other users (for example, /tmp), especially when run by a
       privileged user, that is, root. Be sure that typescript is not a link before running script.

SunOS 5.11							    30 Jan 2004 							 script(1)
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