linux - UNIX sed 命令不删除 cat 输出中的空格

Question

我有一个文件如下。

Hi this is first line
    this is second line
    this is third line

预期是:

Hi this is first line
this is second line
this is third line

我用的是

cat file.txt | sed 's/ //g'

返回，

Hi this is first line
    this is second line
    this is third line

Answer 1

对于可移植的 sed 命令，使用这个:

sed 's/^[[:blank:]]*//' file

[[:blank:]] 匹配空格或制表符。

编辑:使用 awk 删除所有空格:

awk '{$1=$1}1' OFS= file

或 sed:

sed 's/[[:blank:]]*//g' file