(gawk.info.gz) Getline

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 Explicit Input with `getline'
 =============================
 
    So far we have been getting our input data from `awk''s main input
 stream--either the standard input (usually your terminal, sometimes the
 output from another program) or from the files specified on the command
 line.  The `awk' language has a special built-in command called
 `getline' that can be used to read input under your explicit control.
 
    The `getline' command is used in several different ways and should
 _not_ be used by beginners.  The examples that follow the explanation
 of the `getline' command include material that has not been covered
 yet.  Therefore, come back and study the `getline' command _after_ you
 have reviewed the rest of this Info file and have a good knowledge of
 how `awk' works.
 
    The `getline' command returns one if it finds a record and zero if
 it encounters the end of the file.  If there is some error in getting a
 record, such as a file that cannot be opened, then `getline' returns
 -1.  In this case, `gawk' sets the variable `ERRNO' to a string
 describing the error that occurred.
 
    In the following examples, COMMAND stands for a string value that
 represents a shell command.
 

Menu

 
* Plain Getline               Using `getline' with no arguments.
* Getline/Variable            Using `getline' into a variable.
* Getline/File                Using `getline' from a file.
* Getline/Variable/File       Using `getline' into a variable from a
                                 file.
* Getline/Pipe                Using `getline' from a pipe.
* Getline/Variable/Pipe       Using `getline' into a variable from a
                                 pipe.
* Getline/Coprocess           Using `getline' from a coprocess.
* Getline/Variable/Coprocess  Using `getline' into a variable from a
                                 coprocess.
* Getline Notes               Important things to know about `getline'.
* Getline Summary             Summary of `getline' Variants.
 

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