Question

请帮我理解第二行。我理解它增加了公共库，但我不确切地理解它的作用，特别是[ -f ..命令

#!/bin/bash
[ -f ./scripts/commons.sh ] && source ./scripts/commons.sh ||
    { echo "Failed to source common.sh. Check that you are on l2ver dir." && exit 1; }

Answer 1

-f测试其参数是否存在并且是常规文件（例如，不是目录）。

在上面分享的代码段中，它检查./scripts/commons.sh是否为文件，然后source代码（即在相同的shell 中执行）。

Answer 2

这意味着文件./scripts/commons.sh存在然后，如果它存在，文件将由source命令处理 Read this

Answer 3

-f命令检查文件是否退出。 []是bash中的测试语句。

&&确保第二个命令source ./scripts/commons.sh仅在第一个命令成功终止时才会生效。那是文件./scripts/commons.sh存在

例如，如果文件存在

$ls test
test
$[ -f test ]
$echo $?
0
$[ -f test ] && echo "hello world"
hello world

如果不是

$[ -f test ]
$echo $?
1
$[ -f test ] && echo "hello world"
$

Answer 4

基本上，由于逻辑表达式，它是唯一的一行。如果文件存在，-f是bash缩短的测试。 source命令负责从./scripts/commons.sh获取变量。

你有一个逻辑表达式，如：A和B或C.如果./scripts/commons.sh不存在，那么echo和脚本会终止错误。

还有许多其他bash内置文件测试。请看下面的列表：

       -b FILE
              FILE exists and is block special
       -c FILE
              FILE exists and is character special
       -d FILE
              FILE exists and is a directory
       -e FILE
              FILE exists
       -f FILE
              FILE exists and is a regular file
       -g FILE
              FILE exists and is set-group-ID
       -G FILE
              FILE exists and is owned by the effective group ID
       -h FILE
              FILE exists and is a symbolic link (same as -L)
       -k FILE
              FILE exists and has its sticky bit set
       -L FILE
              FILE exists and is a symbolic link (same as -h)
       -O FILE
              FILE exists and is owned by the effective user ID
       -p FILE
              FILE exists and is a named pipe
       -r FILE
              FILE exists and read permission is granted
       -s FILE
              FILE exists and has a size greater than zero
       -S FILE
              FILE exists and is a socket
       -t FD  
              file descriptor FD is opened on a terminal
       -u FILE
              FILE exists and its set-user-ID bit is set
       -w FILE
              FILE exists and write permission is granted
       -x FILE
              FILE exists and execute (or search) permission is granted

使用-f命令混淆安装线

4 个答案: