Linux中printf命令怎么使用

# Linux中printf命令怎么使用

## 一、printf命令概述

`printf`是Linux和Unix系统中一个功能强大的格式化输出命令，它源自C语言中的`printf()`函数。与`echo`命令相比，`printf`提供了更精确的输出控制和更丰富的格式化功能。

### 1.1 printf与echo的区别
- `echo`自动添加换行符，`printf`默认不添加
- `printf`支持格式化字符串
- `printf`可以精确控制输出格式
- `printf`能够处理特殊字符和转义序列

### 1.2 基本语法格式
```bash
printf format-string [arguments...]

printf "Hello, World!\n"

name="Alice"
age=25
printf "Name: %s, Age: %d\n" "$name" "$age"

printf "%s %s %s\n" "Linux" "is" "awesome"

# 控制小数位数
printf "%.2f\n" 3.14159  # 输出3.14

# 指定输出宽度
printf "%10s\n" "hello"  # 右对齐，宽度10
printf "%-10s\n" "hello" # 左对齐，宽度10

# 组合使用
printf "%10.2f\n" 3.14159 # 宽度10，保留2位小数

printf "Column1\tColumn2\tColumn3\n"

printf "Today is %(%Y-%m-%d)T\n" -1

printf "\e[31mRed Text\e[0m\n"
printf "\e[42;30mGreen Background\e[0m\n"

printf "%-20s %-10s %-10s\n" "Name" "Age" "Score"
printf "%-20s %-10d %-10.2f\n" "Alice" 25 89.5
printf "%-20s %-10d %-10.2f\n" "Bob" 30 92.3

for i in {1..20}; do
    printf "[%-20s] %d%%\r" "$(printf '#%.0s' $(seq 1 $i))" "$((i*5))"
    sleep 0.1
done
printf "\n"

num=255
printf "Decimal: %d\nHex: %x\nOctal: %o\n" $num $num $num

today=$(printf "%(%F)T" -1)
echo "Today is $today"

for i in {1..10}; do
    printf "File%02d.txt\n" $i
done
# 输出File01.txt到File10.txt

var='Hello "World"'
printf "%q\n" "$var"  # 输出带引号的字符串

printf "No newline"
printf "Add newline\n"

printf "Completion: 50%%\n"

printf "%s %s\n" "one" "two" "three" "four"
# 输出：
# one two
# three four