PowerShell lets you send one command's output to the next command's input, called piping. This is similar to the idea of nesting functions, but using a linear syntax.
For example, suppose you have function f, g, h, and you want to compute “h(g(f(x)))”. The nested syntax is inconvenient to use. With post-fix notation, for example used in bash, you can write it as: “x | f | g | h”. This is called a pipe, because it is analogous to water flowing thru pipes.
Here are some examples:
# list current dir, sort it dir | sort # list, sort, show first 5 elements dir | sort | select -first 5 # list, sort, select, then format for display dir | sort | select -first 5 | format-table name, length
# list help topics with summary Get-Help about* | Select-Object Name,Synopsis | Format-Table -Auto
# moving png image files to another dir Get-Item $HOME/Documents/*png | Move-Item -Destination $HOME/Pictures/
# filter out bot access from web log, save to file get-content web-log.txt | select-string -notmatch "Googlebot" | out-file -Encoding utf8 -width 999000 web-log2.txt
# piping example on showing processes Get-Process | Select-Object Name Get-Process | Sort-Object ID -descending Get-Process | Where-Object { $_.Handles -ge 500 } | Sort-Object Handles | Format-Table Handles,Name,Description -Auto
Note that the output of PowerShell are .NET objects. They display on screen as formatted text representation. Unlike unix shells, it is not passing text streams.
# using get-member to see object's members dir | get-memberblog comments powered by Disqus