猫文件名|grep“某物"结果“猫:grep:没有这样的文件或目录"；在shell脚本中 [英] cat file_name | grep "something" results "cat: grep: No such file or directory" in shell scripting

问题描述

我编写了shell脚本，该脚本从输入文件读取命令并执行命令.我有这样的命令:

I have written shell script which reads commands from input file and execute commands. I have command like:

cat linux_unit_test_commands | grep "dmesg" 

输入文件中的

.执行shell脚本时出现以下错误消息:

in the input file. I am getting below error message while executing shell script:

cat: |: No such file or directory
cat: grep: No such file or directory
cat: "dmesg": No such file or directory

脚本:

 #!/bin/bash

 while read line
 do
     output=`$line`
     echo $output >> logs
 done < $1

下面是输入文件(example_commands):

Below is input file(example_commands):

ls
date
cat linux_unit_test_commands | grep "dmesg"

执行:./linux_unit_tests.sh example_commands

Execute: ./linux_unit_tests.sh example_commands

请帮助我解决此问题.

推荐答案

在扩展变量后，不会解析特殊字符，例如 | 和"扩展是单词拆分和通配符扩展.如果要完全解析该行，则需要使用 eval :

Special characters like | and " are not parsed after expanding variables; the only processing done after variable expansion is word splitting and wildcard expansions. If you want the line to be parsed fully, you need to use eval:

while read line
do
    output=`eval "$line"`
    echo "$output" >> logs
done < $1

这篇关于猫文件名|grep“某物"结果“猫:grep:没有这样的文件或目录"；在shell脚本中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！