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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 |
END | match after last input line |
pattern1, pattern2, ..., patternn | match if pattern1, pattern2, or patternn match current input line |
pattern1 && pattern2 | match if pattern1 and pattern2 match current input line |
pattern1 || pattern2 | match if pattern1 or pattern2 match current input line |
!pattern | match if pattern does not match current input line |
/regular-expression/ | match if regular-expression matches current input line |
relational-expression | match if relational-expression evaluates to true |
Flow Control Statements:
break | exit from a for or while loop |
continue | execute next for or while loop |
delete variable[expression] | delete element expression from array variable |
do statement while (expression) | execute statement while expression is true |
exit | skip remaining input |
for (expression1; expression2; expression3) statement | execute statement while expression2 is true; loop is usually initialized with expression1 and incremented with expression3 |
for (variable in array) statement | execute statement, setting variable to successive elements in array |
if (expression) statement1 [ else statement2 ] | execute statement1 if expression is true, otherwise execute statement2 |
next | skip rest of the input line |
return[expression] | return value of expression |
system(command) | execute command and return status |
while (expression) statement | execute statement while expression is true |
Input/Output Statements:
close(file) | close file |
getline | set $0 to next input record; set NF, NR, FNR |
getline<file | set $0 to next input from file; set NF |
getline var | set var to next input record; set NR, FNR |
getline variable<file | set variable to next input record from file |
command | getline | pipe output of command into getline |
print current input record | |
print expression | print expression; multiple expressions must be separated with a "," |
print expression>file | print expression to file; multiple expressions must be separated with a "," |
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 |. |
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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