Using -replace on pipes in powershell

catfind and replacepipepowershell

I want to test out a replace before I use it, so I'm trying to write a quick online command to see what the output is. However, I'm not sure what the syntax is. What I want to do is something like

cat file | -replace "a", "b"

What is the correct powershell syntax for this?

I know that I can also do $a = cat file and then do a replace on $a, but I'de like to keep this on one line

Best Answer

This should do the trick, it'll go through all the lines in the file, and replace any "a" with "b", but you'll need to save that back into a file afterwards

cat file | % {$_.replace("a","b")} | out-file newfile

I want to cat a file and output the line number of each line it outputs.

Use the following command:

$counter = 0; get-content .\test.txt | % { $counter++; write-host "`t$counter` $_" }

As pointed out in the comments:

It may be better to use write-output instead of write-host as this allows further processing of the output.
echo is an alias for write-output

So the above command becomes:

$counter = 0; get-content .\test.txt | % { $counter++; echo "`t$counter` $_" }

Example output:

> type test.txt
foo
//approved
bar
// approved
foo
/*
approved
*/
bar

> $counter = 0; get-content .\test.txt | % { $counter++; echo "`t$counter` $_" }
        1 foo
        2 //approved
        3 bar
        4 // approved
        5 foo
        6 /*
        7 approved
        8 */
        9 bar
>

Example output from Cygwin cat -n for comparison:

$ cat -n test.txt
     1  foo
     2  //approved
     3  bar
     4  // approved
     5  foo
     6  /*
     7  approved
     8  */
     9  bar
$

Best Answer

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I want to cat a file and output the line number of each line it outputs.

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