Reading Input Files
In the typical `awk' program, all input is read either from the
standard input (by default the keyboard, but often a pipe from another
command) or from files whose names you specify on the `awk' command
line. If you specify input files, `awk' reads them in order, reading
all the data from one before going on to the next. The name of the
current input file can be found in the built-in variable `FILENAME'
(Note: Built-in Variables.).
The input is read in units called "records", and processed by the
rules of your program one record at a time. By default, each record is
one line. Each record is automatically split into chunks called
"fields". This makes it more convenient for programs to work on the
parts of a record.
On rare occasions you will need to use the `getline' command. The
`getline' command is valuable, both because it can do explicit input
from any number of files, and because the files used with it do not
have to be named on the `awk' command line (Note: Explicit Input with
- * Records
- Controlling how data is split into records.
- * Fields
- An introduction to fields.
- * Non-Constant Fields
- Non-constant Field Numbers.
- * Changing Fields
- Changing the Contents of a Field.
- * Field Separators
- The field separator and how to change it.
- * Constant Size
- Reading constant width data.
- * Multiple Line
- Reading multi-line records.
- * Getline
- Reading files under explicit program control
using the `getline' function.
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