awk-文本处理工具.md

The awk command

Awk is a general-purpose scripting language used for advanced text processing. It is mainly used as a reporting and analysis tool. Unlike most other procedural programming languages, Awk is data-driven, meaning that you need to define a set of operations to be performed on the input text and then it fetches the input data, processes it, and sends the results to standard output.

Syntax

awk [ -F fs ] [ -v var=value ] [ 'prog' | -f progfile ] [ file ... ]

Parameters

• -F fs: Set the input field separator to the regular expression fs.
• -v var=value: Assign the value to the variable var before executing the awk program.
• 'prog': The awk program.
• -f progfile: Specify the file progfile that contains the awk program to be executed.
• file ...: Files to be processed by the specified awk program.

Examples

Suppose the example file example.txt contains the following data:

Bucks Milwaukee    60 22 0.732 
Raptors Toronto    55 24 0.707 
76ers Philadelphia 51 31 0.622
Celtics Boston     33 33 0.598
Pacers Indiana     30 34 0.585

Print the third field of example.txt.

awk '{ print $3 }' example.txt
# 60
# 55
# 51
# 33
# 30

Match the groups that start with R using regular expressions.

awk '/^R/ { print $1,$2,$3,$4 }' example.txt
# Raptors Toronto 55 24

Use BEGIN and END to perform actions before and after processing records. The process is to output groups where the second field contains Tor.

awk 'BEGIN { print "Start Processing" }; $2 ~ /Tor/ {print $1,$2,$3,$4 }; END { print "End Processing" }' example.txt
# Start Processing
# Raptors Toronto 55 24
# End Processing

Daily Question

https://github.com/WindrunnerMax/EveryDay

References

https://linuxize.com/post/awk-command/
https://www.computerhope.com/unix/uawk.htm
https://www.runoob.com/linux/linux-comm-awk.html