How to replace multiple strings in a file using PowerShell

Question

I am writing a script for customising a configuration file  I want to replace multiple instances of strings within this file  and I tried using PowerShell to do the job   It works fine for a single replace  but doing multiple replaces is very slow because each time it has to parse the whole file again  and this file is very large  The script looks like this    original file    path filename abc   destination file     path filename abc new   Get-Content  original file    Foreach-Object          -replace  something1    something1new          Set-Content  destination file   I want something like this  but I don t know how to write it    original file    path filename abc   destination file     path filename abc new   Get-Content  original file    Foreach-Object          -replace  something1    something1aa         -replace  something2    something2bb         -replace  something3    something3cc         -replace  something4    something4dd         -replace  something5    something5dsf         -replace  something6    something6dfsfds          Set-Content  destination file

User · Answer

Assuming you can only have one  something1  or  something2   etc  per line  you can use a lookup table    lookupTable           something1     something1aa       something2     something2bb       something3     something3cc       something4     something4dd       something5     something5dsf       something6     something6dfsfds      original file    path filename abc   destination file     path filename abc new   Get-Content -Path  original file   ForEach-Object        line            lookupTable GetEnumerator     ForEach-Object           if   line -match    Key                         line -replace    Key     Value             break                     Set-Content -Path  destination file   If you can have more than one of those  just remove the break in the if statement

User · Answer

One option is to chain the -replace operations together  The   96  at the end of each line escapes the newline  causing PowerShell to continue parsing the expression on the next line    original file    path filename abc   destination file     path filename abc new   Get-Content  original file    Foreach-Object          -replace  something1    something1aa           -replace  something2    something2bb           -replace  something3    something3cc           -replace  something4    something4dd           -replace  something5    something5dsf           -replace  something6    something6dfsfds          Set-Content  destination file   Another option would be to assign an intermediate variable    x      -replace  something1    something1aa   x    x -replace  something2    something2bb       x

User · Answer

A third option  for a pipelined one-liner is to nest the -replaces   PS gt    ABC  -replace  B   C   -replace  C   D  ADD   And   PS gt    ABC  -replace  C   D   -replace  B   C  ACD   This preserves execution order  is easy to read  and fits neatly into a pipeline   I prefer to use parentheses for explicit control  self-documentation  etc   It works without them  but how far do you trust that    -Replace is a Comparison Operator  which accepts an object and returns a presumably modified object   This is why you can stack or nest them as shown above   Please see   help about operators

User · Answer

With version 3 of PowerShell you can chain the replace calls together     Get-Content  sourceFile    ForEach-Object          replace  something1    something1   replace  somethingElse1    somethingElse2        Set-Content  destinationFile

User · Answer

To get the post by George Howarth working properly with more than one replacement you need to remove the break  assign the output to a variable   line  and then output the variable    lookupTable           something1     something1aa       something2     something2bb       something3     something3cc       something4     something4dd       something5     something5dsf       something6     something6dfsfds      original file    path filename abc   destination file     path filename abc new   Get-Content -Path  original file   ForEach-Object        line            lookupTable GetEnumerator     ForEach-Object           if   line -match    Key                         line    line -replace    Key     Value                     line     Set-Content -Path  destination file

[powershell] How to replace multiple strings in a file using PowerShell

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