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Program Format:
Patterns in program can be associated with a statement to perform if an input line matches the pattern. The format is:
pattern { statement }
A missing pattern always matches, and a missing statement prints the current input line.
Patterns:
| BEGIN
| match before first input line
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| END
| match after last input line
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| pattern1, pattern2, ..., patternn
| match if pattern1, pattern2, or patternn match current input line
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| pattern1 && pattern2
| match if pattern1 and pattern2 match current input line
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| pattern1 || pattern2
| match if pattern1 or pattern2 match current input line
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| !pattern
| match if pattern does not match current input line
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| /regular-expression/
| match if regular-expression matches current input line
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| relational-expression
| match if relational-expression evaluates to true
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Flow Control Statements:
| break
| exit from a for or while loop
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| continue
| execute next for or while loop
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| delete variable[expression]
| delete element expression from array variable
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| do statement while (expression)
| execute statement while expression is true
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| exit
| skip remaining input
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| for (expression1; expression2; expression3) statement
| execute statement while expression2 is true; loop is usually initialized with expression1 and incremented with expression3
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| for (variable in array) statement
| execute statement, setting variable to successive elements in array
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| if (expression) statement1 [ else statement2 ]
| execute statement1 if expression is true, otherwise execute statement2
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| next
| skip rest of the input line
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| return[expression]
| return value of expression
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| system(command)
| execute command and return status
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| while (expression) statement
| execute statement while expression is true
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Input/Output Statements:
| close(file)
| close file
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| getline
| set $0 to next input record; set NF, NR, FNR
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| getline<file
| set $0 to next input from file; set NF
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| getline var
| set var to next input record; set NR, FNR
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| getline variable<file
| set variable to next input record from file
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| command | getline
| pipe output of command into getline
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| print
| print current input record
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| print expression
| print expression; multiple expressions must be separated with a ","
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| print expression>file
| print expression to file; multiple expressions must be separated with a ","
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| printf format expression
| print expression according to C-like format. Multiple expressions must be separated with a ",". Output can also be appended to file using >> or piped to a command using |.
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| printf format expression>file
| print expression to file according to C-like format. Multiple expressions must be separated with a ",". Output can also be appended to file using >> or piped to a command using |.
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