Jul 17
2025-07-17T14:55:00+05:30
by
Asif Mohammad Mollah
Updated
Jul 23
2025-07-23T13:55:08+05:30
1 min
AWK is a powerful pattern scanning and processing command. It is especially useful for text and data extraction, manipulation, and reporting.
Basic Syntax
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| awk 'pattern { action }' file
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- pattern: condition to match (can be omitted)
- action: what to do if pattern matches
Common Built-in Variables
| Variable |
Description |
| $0 |
Entire current line |
| $1..$n |
First to nth field (column) |
| NR |
Number of records (lines) read so far |
| NF |
Number of fields in current record |
| FS |
Field separator (input) |
| OFS |
Output field separator |
Frequently Used Examples
1. Print 1st Column of a File
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| awk '{print $1}' filename
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2. Print Unique Values from Column
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| awk '{print $2}' filename | sort | uniq
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3. Pipe Each Line to a Command
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| awk '{print $0}' filename | while read line; do echo "$line"; done
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4. Add Delimiter for Columns
For example, use : as delimiter:
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| awk '{print $1 ":" $2}' filename
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5. Ignore Lines Matching a Pattern
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| awk '!/pattern_to_ignore/' filename
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Or, using an if condition:
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| awk '{ if ($1 != "skip") print }' filename
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6. Delay Between Each Line Processing
Using a pipe to sleep:
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| awk '{print $1}' filename | while read line; do echo "$line"; sleep 1; done
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Setting Custom Delimiters
- Set Input Field Separator (e.g., comma):
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| awk -F',' '{print $1}' filename
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- Set Output Field Separator:
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| awk 'BEGIN{OFS=":"} {print $1, $2}' filename
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- Example: Filter out comments and execute line
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| awk '!/^#/ {print $1}' script.txt | while read cmd; do eval "$cmd"; done
|
Handy Tips
awk scripts can be multiline using BEGIN, END, and main block.- Can be used in pipelines.
- Fast for CSV and TSV file processing.
Happy AWKing!
