Bash 脚本输出命令未重复找到

Question

我正在尝试创建一个 bash 脚本，它将一些 pacman 查询的输出写入文本文件，主要是本地安装了哪些包，作为依赖项安装的包，孤立的包，以及什么包需要什么依赖。目前，我正在解决一个问题，该问题阻止我编写哪些包需要哪些依赖项。我正在使用以下 bash 代码：

#!/bin/bash

set -e -u

#Switch to PWD
cd /home/$USER/System/scripts/pacman-queries-output/

#Get the current date
DATE=`date +%m%d%Y`

#Pacman Queries
pacman --query -e >pacman_installed$DATE.txt
pacman --query -d >pacman_dependencies$DATE.txt
pacman -Qdt >pacman_orphans$DATE.txt

while read package_desc
do
    package_name=$(echo $package_desc| cut -d' ' -f 1)
    check_if_none=$(pacman -Qi $package_name | grep "Req" | sed -e 's/Required By    : //g')
    if $check_if_none != "Required By     : None"
    then
        echo $package_name >>pacman_required_by$DATE.txt
        pacman -Qi $package_name | grep "Req" | sed -e 's/Required By    : //g' >>pacman_required_by$DATE.txt
    fi
done < $PWD/pacman_installed$DATE.txt

echo 'Completed 'basename

但是，while 循环似乎没有创建 and/or 写入我指定的文本文件，而是在终端中多次回显：

./pacman-queries.sh：第 20 行：必需：找不到命令

以下是运行 bash -x pacman-queries.sh:

时显示的 while 循环迭代之一

+ read package_desc
++ echo aesfix 1.0.1-4
++ cut '-d ' -f 1
+ package_name=aesfix
++ pacman -Qi aesfix
++ grep Req
++ sed -e 's/Required By    : //g'
+ check_if_none='Required By     : None'
+ Required By : None '!=' 'Required By     : None'
pacman-queries.sh: line 20: Required: command not found

任何人都可以提出他们可能必须解决此问题的任何解决方案吗？先感谢您。

Answer 1

if $check_if_none != "Required By     : None"

如果 check_if_none 有字符串：

check_if_none="Required By     : None"

然后扩展为：

if Required By : None != "Required By     : None"

if 尝试执行传递给它的命令。所以它会尝试执行命令Required。而且它没有找到这样的命令。

如何修复：

使用test[ .. ]或[[ ... ]]在bash
总是引用你的变量"$varvar"

if [ "$check_if_none" != "Required By     : None" ]

还有：

不要使用反引号。它们的可读性较差，不能嵌套，并且是 deprecated.

修复后的脚本可能如下所示：

#!/bin/bash

set -e -u

#Switch to PWD
cd "/home/$USER/System/scripts/pacman-queries-output/"

#Get the current date
DATE=$(date +%m%d%Y)

#Pacman Queries
pacman --query -e >"pacman_installed$DATE.txt"
pacman --query -d >"pacman_dependencies$DATE.txt"
pacman -Qdt >"pacman_orphans$DATE.txt"

while IFS= read -r package_desc; do

    package_name=$(echo "$package_desc" | cut -d' ' -f 1)

    # renamed from check_if_none
    # some newlines for readability
    Required=$(
          pacman -Qi "$package_name" | 
          grep "Req" | 
          sed -e 's/Required By    : //g'
    )

    if [ "$Required" != "Required By     : None" ]; then

        echo "$package_name" 
        # runnung `pacman -Q` twice is just throwing cpu cycles...
        echo "$Required"

    fi
# All output goes into required_by - moved it here
# also changed `>>` into `>`
done < "$PWD/pacman_installed$DATE.txt" > "pacman_required_by$DATE.txt"

echo 'Completed 'basename

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