为什么cd不能进入目标文件夹？

Question

编写一个多行别名命令：

alias cdvf='(ID=$(id -u $USER);
             gvfs_uri="mtp:host=Xiaomi_Redmi_10A_IJLZKJLNNRLBSSVO/Internal shared storage/Android/data";
             echo "$gvfs_uri";
             dfolder="/run/user/$ID/gvfs/""$gvfs_uri";
             echo "$dfolder";
             cd "$dfolder")'

跟踪运行时逗号：

set -x

现在将别名粘贴到控制台中，调用我的别名--cdvf:它永远不会进入目标文件夹/Android/data，但是最后一个命令被bash解析为+ cd '/run/user/1000/gvfs/mtp:host=Xiaomi_Redmi_10A_IJLZKJLNNRLBSSVO/Internal shared storage/Android/data'。

debian@debian:~$ cdvf
++ id -u debian
+ ID=1000
+ gvfs_uri='mtp:host=Xiaomi_Redmi_10A_IJLZKJLNNRLBSSVO/Internal shared storage/Android/data'
+ echo 'mtp:host=Xiaomi_Redmi_10A_IJLZKJLNNRLBSSVO/Internal shared storage/Android/data'
mtp:host=Xiaomi_Redmi_10A_IJLZKJLNNRLBSSVO/Internal shared storage/Android/data
+ dfolder='/run/user/1000/gvfs/mtp:host=Xiaomi_Redmi_10A_IJLZKJLNNRLBSSVO/Internal shared storage/Android/data'
+ echo '/run/user/1000/gvfs/mtp:host=Xiaomi_Redmi_10A_IJLZKJLNNRLBSSVO/Internal shared storage/Android/data'
/run/user/1000/gvfs/mtp:host=Xiaomi_Redmi_10A_IJLZKJLNNRLBSSVO/Internal shared storage/Android/data
+ cd '/run/user/1000/gvfs/mtp:host=Xiaomi_Redmi_10A_IJLZKJLNNRLBSSVO/Internal shared storage/Android/data'
debian@debian:~$ 
debian@debian:~$ cd '/run/user/1000/gvfs/mtp:host=Xiaomi_Redmi_10A_IJLZKJLNNRLBSSVO/Internal shared storage/Android/data'
+ cd '/run/user/1000/gvfs/mtp:host=Xiaomi_Redmi_10A_IJLZKJLNNRLBSSVO/Internal shared storage/Android/data'
debian@debian:/run/user/1000/gvfs/mtp:host=Xiaomi_Redmi_10A_IJLZKJLNNRLBSSVO/Internal shared storage/Android/data$ 
debian@debian:/run/user/1000/gvfs/mtp:host=Xiaomi_Redmi_10A_IJLZKJLNNRLBSSVO/Internal shared storage/Android/data$ 

将最后一行复制到终端并运行，它进入目标文件夹，为什么cdvf不能进入目标文件夹/Android/data

Answer 1

它正在更改到该目录。但是，您可以在别名中使用()：这将创建一个子subshell。在子shell中，您位于正确的目录中，但随后子shell退出，并且您位于以前所在的目录中(在“当前”shell中)。

从别名中删除括号。

我假设您使用括号来避免使用变量污染shell。您需要使用一个函数来代替：

cdvf() {
    local ID gvfs_uri dfolder
    ID=$(id -u "$USER")
    gvfs_uri="mtp:host=Xiaomi_Redmi_10A_IJLZKJLNNRLBSSVO/Internal shared storage/Android/data"
    echo "$gvfs_uri"
    dfolder="/run/user/$ID/gvfs/$gvfs_uri"
    echo "$dfolder"
    cd "$dfolder"
}

正如bash手册在别名中说的那样

对于几乎所有的用途，shell函数都比别名更好。