Malin Freeborn
ba8026e0c3
input examples are now given as ```bash input $ARG1 ``` While outputs use md's '> ' sign as a quote.
1.5 KiB
| title | tags | ||
|---|---|---|---|
| awk |
|
Basics
See a file's contents:
Return full contents of a string:
awk '{ print }' file
Print the first and second column:
awk '{print$1$2}'
Return every line with the word 'the' (like grep):
awk '/the/{print}' file
Print everything containing a lowercase letter:
awk '/[a-z]/{print}' file
Same with numbers [0-9], or using a caret we can show lines starting with a number - ^[0-9], or ending with an uppercase letter - $[A-Z].
Conditionals
awk '{ if($1 ~ /123/) print }' file
Check if the first column is equal to 1 or 2 or 3, and if so then print that line.
Grep for 'hawk' in a story:
awk '/hawk/' story.txt
Return any line with one or more "&" sequences:
awk '/&+/' script.sh
The pipe is used for 'or', so 'Orcs or drums' would be:
awk '/Orcs|Drums/' story.txt
Basic variables are:
-
FS = Input field separator
-
OFS = Output field separator
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NF = Number of fields on the current line
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NR = Number of records in the current file
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RS = Record separator
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ORS = Output record separator
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FILENAME = the file you're looking at.
So you can count the number of lines in a file, by referencing the number of 'end line' statements:
awk 'END{print NR}' story.txt
Print line 2 from story.txt
awk '{if(NR~/^2$/)print}' story.txt
Same, but any line starting with "2":
awk '{if(NR~/^2/)print}' story.txt