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Shell Programming and Scripting

-z means in unix

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# 1  
Old 09-26-2011
-z means in unix
Hi All, I am very new to shell scripting.
Please tell me what is the meansing for below if condition.

Code:
if [[ -z $FREQUENCY_MODE || "$FREQUENCY_MODE" != "A" && "$FREQUENCY_MODE" != "D" ]]

Thanks in advance...

Regads,
dathu
Last edited by DukeNuke2; 09-26-2011 at 07:07 PM..
# 2  
Old 09-26-2011
this means :
if $FREQUENCY_MODE variable is empty
OR $FREQUENCY_MODE is different from "A"
AND $FREQUENCY_MODE is different from "D"
# 3  
Old 09-26-2011
Thanks for the quick reply..

-z checks whether the variable is empty or not?

Thanks for the information.
# 4  
Old 09-26-2011
Yes,
if [[ -z $VAR ]] condition is true if $VAR is empty
if [[ -n $VAR ]] condition is true if $VAR is not empty
This User Gave Thanks to ctsgnb For This Post:
pdathu
# 5  
Old 09-26-2011
read "man test" for mor information about the condition topic...

and please use code tags for terminal output or script sniplets!
This User Gave Thanks to DukeNuke2 For This Post:
pdathu
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