powershell - 如何将 Powershell 命令的输出用作另一个 Powershell 命令的参数?
问题描述
我想折叠这些 Powershell 命令:
$colour = ""
$colour1 = "Red"
$colour2 = "Green"
if ($var -eq 0) {
# failure
$colour = $colour1
} Else {
# success
$colour = $colour2
}
Write-Host ("Answer = " + $var) -ForegroundColor $colour
在一行中,使用if
上面表达式的输出作为 的输入参数Write-Host
,例如:
Write-Host ("Answer = " + $var) -ForegroundColor &{if ($var -eq 0) {'Red'} else {'Green'}
我尝试过但失败的事情:
Write-Host ("Answer = " + $var) -ForegroundColor &{if ($var -eq 0) {'Red'} else {'Green'}
Write-Host ("Answer = " + $var) -ForegroundColor `&{if ($var -eq 0) {'Red'} else {'Green'}`
Write-Host ("Answer = " + $var) -ForegroundColor `{if ($var -eq 0) {'Red'} else {'Green'}`
Write-Host ("Answer = " + $var) -ForegroundColor &`{if ($var -eq 0) {'Red'} else {'Green'}`
Write-Host ("Answer = " + $var) -ForegroundColor (&`{if ($var -eq 0) {'Red'} else {'Green'}`)
Write-Host ("Answer = " + $var) -ForegroundColor `{if ($var -eq 0) {return 'Red'} else {return 'Green'}`
Write-Host ("Answer = " + $var) -ForegroundColor `&{if ($var -eq 0) {return 'Red'} else {return 'Green'}`
Write-Host ("Answer = " + $var) -ForegroundColor `&{if ($var -eq 0) {return "Red"} else {return "Green"}`
Write-Host ("Answer = " + $var) -ForegroundColor &{if ($var -eq 0) {return "Red"} else {return "Green"}
Write-Host ("Answer = " + $var) -ForegroundColor &{if ($var -eq 0) {return "Red"} else {return "Green"}}
Write-Host ("Answer = " + $var) -ForegroundColor `&{if ($var -eq 0) {return "Red"} else {return "Green"}}`
Write-Host ("Answer = " + $var) -ForegroundColor &`{if ($var -eq 0) {return "Red"} else {return "Green"}}`
Write-Host ("Answer = " + $var) -ForegroundColor `{if ($var -eq 0) {return "Red"} else {return "Green"}}`
Write-Host ("Answer = " + $var) -ForegroundColor `if ($var -eq 0) {return "Red"} else {return "Green"}`
解决方案
要将整个语句(例如if
)的输出作为命令参数传递,请将它们括在$(...)
子表达式运算符中。
一个简化的例子:
# Note the use of $(...) around the `if` statement.
PS> $var = 0; Write-Host $(if ($var -eq 0) { 'zero' } else { 'nonzero' })
zero
请注意,如果只需要expression或command的输出,则使用(...)
,分组运算符就足够了(并且没有副作用)。
if
例如,语句的 PowerShell (Core) 7+ 替代方案是三元运算符,其用途是表达式:
# PowerShell (Core) 7+ only.
# Since an expression is used, (...) is sufficient.
PS> $var = 0; Write-Host ($var -eq 0 ? 'zero' : 'nonzero')
zero
对于命令(管道),(...)
也足够了。
# Since a command is used, (...) is sufficient.
Write-Output (Get-Item *.txt | Where-Object Length -ge 1kb)
有关$(...)
vs.的更多信息(...)
,请参阅此答案。
推荐阅读
- c# - WCF LocalChannel,在一个服务内调用一个服务,同一个应用,同一个机器
- javascript - 移动文本后不再反应
- sql - convert_timezone 对雪花 sql 中的 timestampdiff 没有意义
- html - 通过引用邻居部分的条件 CSS 选择器
- c# - 根据登录的用户 ID 分隔列表
- java - 如何添加 myApp 以使用完成操作?
- python - 尝试从文本中提取表情符号时出现空白列
- python - 如何使用包含文件路径的 2 项元组列表
- python - 重构 Python 类以采用动态参数而不显着改变调用模式
- reactjs - react.js如何形成卡片组