awk

Print the fifth column (a.k.a. field) in a space-separated file

$ awk '{print $5}' [path/to/file] 

$ awk '/[foo]/ {print $2}' [path/to/file] 

$ awk -F ',' '{print $NF}' [path/to/file]

$ awk '{s+=$1} END {print s}' [path/to/file]

$ awk '{if ($1 == "foo") print "Exact match foo"; else if ($1 ~ "bar") print "Partial match bar"; else print "Baz"}' [path/to/file]

$ awk '($10 >= [min_value] && $10 <= [max_value])'

awk [-F fs] [-v var=val] [-f progfile] [--posix] [--] 'program' [files]

awk is a pattern-scanning and text-processing language designed for extracting and transforming structured data. It reads input line by line, splits each line into fields, and applies user-defined rules consisting of patterns and actions.
An awk program is a sequence of pattern { action } rules. For each input line, awk tests the patterns and executes the associated actions for any that match. If no pattern is given, the action applies to every line. If no action is given, matching lines are printed.
Fields are accessed as $1, $2, etc., with $0 representing the entire line. The default field separator is whitespace, changeable with -F. Built-in variables include NR (current line number), NF (number of fields in current line), FS (field separator), and OFS (output field separator).
Special patterns BEGIN and END execute actions before and after all input is processed, useful for initialization and summary output. Awk supports variables, arrays, arithmetic, string functions, printf formatting, and control flow statements, making it a complete programming language for text processing.

-F _fs_

Field separator (fs); default whitespace or TAB

Read awk program from file instead of command line

Assign val to var before program runs (repeatable)

End options; treat following as filenames

Print version and exit (gawk)

Print help and exit (gawk)

Enforce POSIX compatibility (gawk)

Limit function args to n (debugging; gawk)

Limit record size to n bytes (debugging; gawk)

Use original awk behavior (gawk)

\$0: Full line
\$1: First field
NF: Fields count
NR: Record (line) number
Use \$(n) for nth field

Different awk implementations (gawk, mawk, nawk) have varying feature sets. Regular expressions and string functions may behave differently across implementations. Associative arrays are unordered. Floating-point arithmetic may produce rounding errors. Very large files are processed efficiently but complex programs with many arrays can consume significant memory.

awk was created by Alfred Aho, Peter Weinberger, and Brian Kernighan at Bell Labs in 1977, with the name derived from their initials. It was redesigned and expanded in 1985 as "new awk" (nawk). GNU awk (gawk) added many extensions including networking and internationalization. Awk is a standard POSIX utility available on virtually all Unix-like systems.

sed(1), grep(1), cut(1), perl(1), gawk(1)