Text Processing
How to Use awk to Join Two Files on a Key Without Surprises
Join two files on a key with awk: inner and left joins, duplicate keys, composite keys, output separators and when the join command is the better choice.
6 min read
Tag
awk
13 posts
Text Processing
How to Use awk With Multiple Files and NR FNR Step by Step
Read two files in one awk program with NR == FNR: load a lookup table, annotate lines, filter by a list and avoid the empty file trap.
6 min read
Text Processing
How to Use awk Patterns Ranges and BEGIN and END Blocks
Understand awk pattern action pairs: regex and comparison patterns, range patterns, BEGIN and END blocks, next and exit, and overlapping rules.
6 min read
Text Processing
How to Use awk Associative Arrays for Counting and Grouping
Count, group and deduplicate with awk associative arrays: count[$1]++, loop over keys, sort the output, test membership and use composite keys.
5 min read
Regular Expressions
How to Use Regex in awk Matching and match Function
Use regex in awk: the tilde operator, patterns between slashes, dynamic regex strings, the match function with RSTART and RLENGTH, and gsub with ampersand.
6 min read
Text Processing
How to Use awk to Sum Average and Count Columns the Safe Way
Sum, average, count, minimum and maximum a column with awk: skip headers, guard against non-numeric rows and empty input, and group the totals by a key.
6 min read
Text Processing
How to Use awk Fields Separators and Printf Step by Step
Learn awk fields and printf: $1 and NF, set the field separator with -F or FS, control the output separator, align columns and rebuild a line.
6 min read
Text Processing
How to Use awk User Defined Functions and Math the Safe Way
Write awk user functions: parameters and local variables, recursion, libraries, numeric precision, rounding and the string versus number pitfalls.
6 min read
Text Processing
How to Use gawk Features Beyond POSIX awk the Safe Way
Gawk features beyond POSIX awk: arrays of arrays, asort, gensub, strftime, FPAT, networking, include and the portability costs of using them.
6 min read
Text Processing
How to Pass Shell Variables Into awk Safely With Real Output
Pass shell variables into awk safely with -v and ENVIRON instead of splicing them into the program, and avoid quoting, escape-sequence and injection bugs.
6 min read
Text Processing
How to Use awk With CSV Files and Quoted Fields the Safe Way
Process CSV with awk when fields hold quoted commas: why -F, fails, gawk FPAT, the --csv flag in gawk 5.3, headers and when to use csvkit or Python.
6 min read
Text Processing
How to Use awk to Parse Logs and Build Reports the Safe Way
Use awk to parse logs and build reports: field splitting, counting by key, sums and averages, time buckets, sorted summaries and END blocks.
6 min read