linux:bash

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linux:bash [2022/02/11 11:02] – [Generalities] mhlinux:bash [2022/02/28 14:54] (current) – mh
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 Bash is **not a strict interpreter**.  Bash is **not a strict interpreter**. 
  
-Beware of the ambiguity we are used to while expressing ourselves with human languages.+**Beware of the ambiguity** we are used to while expressing ourselves with human languages.
  
-The discipline of writing clear, safe and precise code lies heavily upon the user. +The **discipline of writing clear, safe and precise code** lies heavily upon the user. 
  
-**Don't write bad bash code.**+__**Don't write bad bash code.**__
 </WRAP> </WRAP>
  
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 Many command types are syntax sugar: their effect can be achieved differently, but they exist to make the job easier.  Many command types are syntax sugar: their effect can be achieved differently, but they exist to make the job easier. 
 </WRAP> </WRAP>
 +
 +==== Variables ====
 +
 +Before a command's name you can insert one or many ''var=value'' assignments. These variables will apply only to that one command.
  
 ==== Basic commands ==== ==== Basic commands ====
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 Bash performs a search using this name and looks for :  Bash performs a search using this name and looks for : 
-  *alias (first)+  *alias (before anything else)
   *functions   *functions
   *built-in commands   *built-in commands
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 $ echo $name $ echo $name
 john john
 +</code>
 +----
 +
 +=== type ===
 +
 +Displays information on a command, and where it is stored.
 +
 +//Note that the **type** command and the **which** program are different and give different outputs//
 +
 +**Example**
 +<code bash>
 +$ type ls
 +ls is aliased to 'ls -al'
 </code> </code>
 ---- ----
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 They can be a filename, a variable name, the name of a program or just a litteral. They can be a filename, a variable name, the name of a program or just a litteral.
 +
 +Multiple arguments can be used, separated by a blank space
 </WRAP> </WRAP>
  
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 There can be **no whitespace** around the = operator !  There can be **no whitespace** around the = operator ! 
  
-If a whitespace is required in the variable, use '' quotes to create a literal+If a whitespace is required in the variable, use 'single quotes' to create a literal
 </WRAP> </WRAP>
  
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 As a result, both file descriptors are connected to the same stream. As a result, both file descriptors are connected to the same stream.
  
 +Be careful not to write something like ''$ ls -l a b >myfiles.ls 2>myfiles.ls'' as due to the way streams are handled they will most likely end up mixing up and garbling the file 'myfiles.ls'
 </WRAP> </WRAP>
  
  • linux/bash.1644573735.txt.gz
  • Last modified: 2022/02/11 11:02
  • by mh