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Top Forums UNIX for Dummies Questions & Answers Variable check for existence ? Post 302098633 by samit_9999 on Tuesday 5th of December 2006 02:39:35 PM
Old 12-05-2006
Variable check for existence ?

Hi ,

I have a script wherein i have a For Loop.
Within this for loop i create a variable and assign it a value.

The script goes to a For Loop only if certain conditions are met , which means the variable may or may not exists.

However down the line in the script i have to check if that variable exists on or not.

How do i check this

I tried this but the script fails with the following error "Specify a parameter with this command."
if [ -s ${FILE_LIST} ]
then
echo "Variable Exist"
fi

Please help

Sam
 

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script(1)						      General Commands Manual							 script(1)

NAME
script - Makes a transcript of terminal session SYNOPSIS
script [-a] [file] The script command makes a transcript of everything printed on your terminal. OPTIONS
Appends the transcript to file rather than writing it to file. OPERANDS
The name of an output file that will contain the transcript of the session. If this parameter is omitted, the file typescript is written. DESCRIPTION
The transcript is written to file, or appended to file if the -a option is given. If no file name is given, the transcript is saved in the file typescript. The script ends when the forked shell exits. This program is useful when you are using a CRT and want a hard-copy record of the dialog (for example, a technical writer might create an example of a working session this way). If you specify the -a option and the file does not exist, it is created. If you do not specify the -a option and the file exists, it is replaced. RESTRICTIONS
The script command requires a streams based terminal. In single user mode, streams may not be enabled. Under these circumstances, script will exit with no action. If you are the superuser and need to run this command in single user mode, use the following special instruc- tions. Enabling Streams If it is necessary to enable a streams environment in the single user mode, enter the command /sbin/init.d/streams. This command is avail- able to the superuser only. SEE ALSO
Commands: autopush(8), cat(1), echo(1), strsetup(8), tee(1) System Administration script(1)
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