coreutils: printenv invocation

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1 19.3 ‘printenv’: Print all or some environment variables
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1 ‘printenv’ prints environment variable values.  Synopsis:
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1      printenv [OPTION] [VARIABLE]...
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1    If no VARIABLEs are specified, ‘printenv’ prints the value of every
1 environment variable.  Otherwise, it prints the value of each VARIABLE
1 that is set, and nothing for those that are not set.
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11    The program accepts the following option.  Also see ⇒Common
 options.
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1 ‘-0’
1 ‘--null’
1      Output a zero byte (ASCII NUL) at the end of each line, rather than
1      a newline.  This option enables other programs to parse the output
1      even when that output would contain data with embedded newlines.
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1    Exit status:
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1      0 if all variables specified were found
1      1 if at least one specified variable was not found
1      2 if a write error occurred
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