Shell脚本，将命令值保存到变量中

发布于 2024-11-27 21:52:51 字数 439 浏览 1 评论 0原文

我正在尝试在同一行中打印 VARI 的值，后跟逗号，以便我可以拥有这些值的 csv 文件，但我无法保存 VARI = 'cat 文件名 |头-1 | cut -d, -f${i}'

i=0
while (( i<130)) ;
do
  if [[ $i -eq 1 ||  $i -eq 9 || $i -eq 12 || $i -eq 23 || $i -eq 25 || $i -eq 29 ]]
  then
    VARI = 'cat filename | head -1 | cut -d, -f${i}'
    echo  "$VARI ,"   
  fi
  let i=$i+1;
done

预期输出是

4,abc,5,8,xyz,9

请让我知道我做错了什么，谢谢！

原文

I am trying to print the value of VARI in the same line followed by a comma, so that i can have a csv file of these values, but i m not able to save the value of
VARI = 'cat filename | head -1 | cut -d, -f${i}'

i=0
while (( i<130)) ;
do
  if [[ $i -eq 1 ||  $i -eq 9 || $i -eq 12 || $i -eq 23 || $i -eq 25 || $i -eq 29 ]]
  then
    VARI = 'cat filename | head -1 | cut -d, -f${i}'
    echo  "$VARI ,"   
  fi
  let i=$i+1;
done

output expected is

4,abc,5,8,xyz,9

Please let me know what i am doing wrong, thanks!

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救赎№ 2024-12-04 21:52:51

使用反引号（或可以嵌套的 $()），而不是单引号：

VARI=`cat filename | head -1 | cut -d, -f${i}` # or:
VARI=$(cat filename | head -1 | cut -d, -f${i})

确保变量名称、等号和变量值之间没有空格。

VAR = x # executes program "VAR" with 2 parameters: "=" and "x"
VAR =x  # executes program "VAR" with a single parameter: "=x"
VAR= x  # executes program "x" with environment variable "VAR" set to an empty value
VAR=x   # assigns value "x" to shell variable "VAR"

资源：POSIX 的 2.10.2 Shell 语法规则。 1-2017 规范。

Use backticks (or $() which can be nested), not single quotes:

VARI=`cat filename | head -1 | cut -d, -f${i}` # or:
VARI=$(cat filename | head -1 | cut -d, -f${i})

Make sure to not have spaces between the variable name, the equal sign, and the variable value.

VAR = x # executes program "VAR" with 2 parameters: "=" and "x"
VAR =x  # executes program "VAR" with a single parameter: "=x"
VAR= x  # executes program "x" with environment variable "VAR" set to an empty value
VAR=x   # assigns value "x" to shell variable "VAR"

Resources: 2.10.2 Shell Grammar Rules of the POSIX.1-2017 specification.

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