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grep 不会将 sed 输出处理为换行符分隔列表

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grep 不会将 sed 输出处理为换行符分隔列表

今天玩的时候，我试图让 grep 消耗......的输出

$(apt-cache rdepends hunspell-fr | sed -e 's/^\s*|\?//' -e 1s/^/\'/g -e \$s/$/\'/)

...作为嵌套在单引号内的换行符分隔模式列表。当我运行上面的命令，然后简单地将结果输出复制/粘贴到新的 grep 命令中时，它的行为符合预期......

nohatsatthetable@debian:~$ dpkg -l | grep 'hunspell-fr
Reverse Depends:
hunspell-fr-classical
thunderbird-l10n-fr
firefox-esr-l10n-fr
thunderbird-l10n-fr
task-french-desktop
hunspell-fr-revised
hunspell-fr-revised
hunspell-fr-comprehensive
hunspell-fr-comprehensive
hunspell-fr-classical
firefox-esr-l10n-fr'

ii  firefox-esr-l10n-fr                    102.4.0esr-1~deb11u1             all          French language package for Firefox ESR
ii  hunspell-fr                            1:7.0-1                          all          French dictionary for hunspell (dependency package)
ii  hunspell-fr-classical                  1:7.0-1                          all          French dictionary for hunspell (classical version)
ii  task-french-desktop                    3.68+deb11u1                     all          French desktop

然而，当我运行以下单行代码时（在我看来，它在功能上应该是相同的），grep 仅将第一行解释为模式，将所有后续行（或第二行情况下的单词）解释为要在其中搜索模式的目录或文件...

nohatsatthetable@debian:~$ dpkg -l | grep $(apt-cache rdepends hunspell-fr | sed -e 's/^\s*|\?//' -e 1s/^/\'/g -e \$s/$/\'/)
grep: Reverse: No such file or directory
grep: Depends:: No such file or directory
grep: hunspell-fr-classical: No such file or directory
grep: thunderbird-l10n-fr: No such file or directory
grep: firefox-esr-l10n-fr: No such file or directory
grep: thunderbird-l10n-fr: No such file or directory
grep: task-french-desktop: No such file or directory
grep: hunspell-fr-revised: No such file or directory
grep: hunspell-fr-revised: No such file or directory
grep: hunspell-fr-comprehensive: No such file or directory
grep: hunspell-fr-comprehensive: No such file or directory
grep: hunspell-fr-classical: No such file or directory
grep: firefox-esr-l10n-fr': No such file or directory

为什么它会这样？

答案1

是的，正如@提到的善行难陀 ，引号是强制性的：

$ dpkg -l |
    grep "$(apt-cache rdepends hunspell-fr |
        sed -e 's/^\s*|\?//' -e 1s/^/\'/g -e \$s/$/\'/
 )"

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