How Linux Works:Shell 编程

摘要

  • Overview
  • BASIC
  • key words:echo、grep、awk、xargs
  • functions & parameters
  • user environment: crontabs
  • concurrent: threads
  • Application

Overview

When to Use Shell Scripts

Shell Script Basics

shell-startup

User Environments

Key Words

Echo

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$ echo 'foo:123:bar:789' | awk -F: '{print $2,$3}'
123 bar

$ # second field where input field separator is :
$ echo 'foo:123:bar:789' | awk -F: '{print $2}'
123

$ # last field
$ echo 'foo:123:bar:789' | awk -F: '{print $NF}'
789

$ # first and last field
$ # note the use of , and space between output fields
$ echo 'foo:123:bar:789' | awk -F: '{print $1, $NF}'
foo 789

$ # second last field
$ echo 'foo:123:bar:789' | awk -F: '{print $(NF-1)}'
bar

$ # use quotes to avoid clashes with shell special characters
$ echo 'one;two;three;four' | awk -F';' '{print $3}'
three

$ echo 'Sample123string54with908numbers' | awk -F'[0-9]+' '{print $2}'
string

Grep

AWK

Xargs

Application

文本查找

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$ grep -rn "Hello" *

Template

扩展阅读

电子书《Linux Perf Master》

扩展阅读:性能诊断指南

扩展阅读:How Linux Works

扩展阅读:动态追踪技术

参考文献

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