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syntax:pe [2017/04/22 03:24] fgrose [Search and replace] |
syntax:pe [2018/07/24 19:53] (current) nicolae Fixed typo |
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| __Why does the first one fail?__ It prints nothing, because a parameter (variable) named "''WORDs''" is undefined and thus printed as "" (//nothing//). Without using braces for parameter expansion, Bash will interpret the sequence of all valid characters from the introducing "''$''" up to the last valid character as name of the parameter. When using braces you just force Bash to **only interpret the name inside your braces**. | __Why does the first one fail?__ It prints nothing, because a parameter (variable) named "''WORDs''" is undefined and thus printed as "" (//nothing//). Without using braces for parameter expansion, Bash will interpret the sequence of all valid characters from the introducing "''$''" up to the last valid character as name of the parameter. When using braces you just force Bash to **only interpret the name inside your braces**. | ||
| - | Also, please remember, that **parameter names are** (like nearly everything in UNIX(r)) **case sentitive!** | + | Also, please remember, that **parameter names are** (like nearly everything in UNIX(r)) **case sensitive!** |
| The second form with the curly braces is also needed to access positional parameters (arguments to a script) beyond ''$9'': | The second form with the curly braces is also needed to access positional parameters (arguments to a script) beyond ''$9'': | ||
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| * => ''THIS IS SOME TEXT'' | * => ''THIS IS SOME TEXT'' | ||
| * ''echo "${array[2]^^}"'' | * ''echo "${array[2]^^}"'' | ||
| - | * => ''TEXT'' | + | * => ''SOME'' |
| ===== Variable name expansion ===== | ===== Variable name expansion ===== | ||