Linux parameter substitution, query login user instructions

1. xargs [ -0EPN] command: Generate parameters for an instruction, parameters:

1)-0: If the input stdin contains special characters, for example ', \, space, this parameter can be restored to a general parameter

2)-e:EOF, followed by a string, when Xargs parses the string, it stops execution (the instruction is executed).

3)-P: When executing the argument of each instruction , the user will be asked

4)-n: The following number of times, each command command execution, to use a few parameters. That is, instructions are executed in batches, and several parameters are called per batch.

2.finger [-SLP] [ user @ hostname ]: Query the user information currently logged in, Parameters:

1)-S: Display the user's registration name, actual name, terminal name, write status, stasis time, login time and other information

2)-L: In addition to the information displayed with the-S option, the user home directory, login shell, message status and other information are displayed, as well as the. Plan in the user's home directory . Project, contents of the . Forward file

3)-P: Except that the. plan file and the. project fileare not displayed , and the-L is the same

3.-:- number can take the standard input, as the parameters of the pipeline directive, especially used to take the last pipeline command generated files, as the file name of the directive. eg:

TAR–CVF/HOME|TAR–XVF-

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Linux parameter substitution, query login user instructions