12 lines
608 B
Text
12 lines
608 B
Text
--------------------- Table 5.3 ---------------------
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$var value of var; nothing if var is undefined
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${var} same; useful if alphanumerics follows variable name
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${var-thing} value of var if defined; otherwise thing.
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$var unchanged.
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${var=thing} value of var if defined; otherwise thing.
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If undefined, $var set to thing
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${var?message} if defined, $var. Otherwise print message
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and exit shell. if Message empty, print:
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var: parameter not set
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${var+thing} thing if $var defined, otherwise nothing
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