Why is -replace not working as described in this powershell script?

Question

The input text from allacts.txt is:

institutionId: blah blah,name: 1st thing,laestabNo: blah blah   institutionId: blah blah,name: 2nd thing,laestabNo: blah blah, [lots more things]   institutionId: blah blah,name: last thing,laestabNo: blah blah

The desired output is:

1st thing,laestabNo: blah blah  2nd thing,laestabNo: blah blah, [lots more things]  last thing,laestabNo: blah blah

The command I am using within a powershell script:

Powershell -NoProfile "(Get-Content -Raw .\allacts.txt) -replace 'institutionid.*,name', '' | Out-File -FilePath allacts.txt -Force -Encoding ASCII"

What I actually get is:

last thing,laestabNo:blah blah

And nothing else. What am I doing wrong?

in regex, the . means one character. the * means zero or more of the previous character. so you are telling it to replace EVERYTHING from the 1st institutionid to the last ,name. [grin] take a look at "greedy & lazy matches" for how to limit that. — Lee_Dailey
– Lee_Dailey, Commented Apr 8, 2021 at 19:02
Thanks yeah I see that now. Just goes to show a little bit of RTFM sometimes beats hours of head-keyboard-smacking. — Ne Mo
– Ne Mo, Commented Apr 9, 2021 at 10:21
you are most welcome! glad to have helped a little bit ... [grin] — Lee_Dailey
– Lee_Dailey, Commented Apr 9, 2021 at 13:20

postanote · Accepted Answer · 2021-04-08 20:53:48Z

1

Your regex is not correct for your use case. You mean this...

$SomeString = 'institutionId: blah blah,name: 1st thing,laestabNo: blah blah   institutionId: blah blah,name: 2nd thing,laestabNo: blah blah, [lots more things]   institutionId: blah blah,name: last thing,laestabNo: blah blah'
Clear-Host
# RegEx to replace all text string patterns and the text between them
$SomeString -Replace '(institutionId: ).*?(name: )'
# Results
<#
1st thing,laestabNo: blah blah   2nd thing,laestabNo: blah blah, [lots more things]   last thing,laestabNo: blah blah
#>

edited Apr 8, 2021 at 20:53

answered Apr 8, 2021 at 20:48

postanote

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