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Top Forums UNIX for Beginners Questions & Answers What is the meaning the $ special character? Post 303006460 by Scrutinizer on Thursday 2nd of November 2017 11:21:05 AM
Old 11-02-2017
Hi see here: The Open Group Base Specifications Issue 7, 2016 Edition

Quote:
In the shell command language, an entity that stores values. There are three types of parameters: variables (named parameters), positional parameters, and special parameters. Parameter expansion is accomplished by introducing a parameter with the '$' character.
Note:
See also XCU Parameters and Variables.

--
"Parameter expansion" is the way to get the value that is stored in a parameter ( for example a variable )

So for example if you have a variable foo and you give it the value bar
Code:
foo=bar

, then the variable foo contains the value bar.
Then, to get the content of the variable foo, you prepend a $ sign:
Code:
echo "$foo"
bar


Last edited by Scrutinizer; 11-02-2017 at 12:28 PM..
 

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environ(4)							   File Formats 							environ(4)

NAME
environ, pref, variables - user-preference variables files for AT&T FACE SYNOPSIS
$HOME/pref/.environ $HOME/pref/.variables $HOME/FILECABINET/.pref $HOME/WASTEBASKET/.pref DESCRIPTION
The .environ, .pref, and .variables files contain variables that indicate user preferences for a variety of operations. The .environ and .variables files are located under the user's $HOME/pref directory. The .pref files are found under $HOME/FILECABINET, $HOME/WASTEBASKET, and any directory where preferences were set via the organize command. Names and descriptions for each variable are presented below. Vari- ables are listed one per line and are of the form variable=value. .environ Variables Variables found in .environ include: LOGINWIN[1-4] Windows that are opened when FACE is initialized. SORTMODE Sort mode for file folder listings. Values include the following hexadecimal digits: 1 Sorted alphabetically by name. 2 Files most recently modified first. 800 Sorted alphabetically by object type. The values above may be listed in reverse order by ORing the following value: 1000 List objects in reverse order. For example, a value of 1002 will produce a folder listing with files LEAST recently modified displayed first. A value of 1001 would produce a "reverse" alphabetical by name listing of the folder. DISPLAYMODE Display mode for file folders. Values include the following hexadecimal digits: 0 File names only. 4 File names and brief description. 8 File names, description, plus additional information. WASTEPROMPT Prompt before emptying wastebasket (yes/no?). WASTEDAYS Number of days before emptying wastebasket. PRINCMD[1-3] Print command defined to print files. UMASK Holds default permissions with which files will be created. .pref Variables Variables found in .pref are the following: SORTMODE Contains the same values as the SORTMODE variable described in .environ above. DISPMODE Contains the same values as the DISPLAYMODE variable described in .environ above. .variable Variables Variables found in .variables include: EDITOR Default editor. PS1 Shell prompt. SunOS 5.10 3 Jul 1990 environ(4)
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