PowerShell Select-String cmdlet

The Select-String is a cmdlet supported by PowerShell to select a text/pattern in a string. The Select-String is also referred to as the grep equivalent, where grep is a UNIX-based command to search for patterns. With this command, you can search all the available matches or can also add a limit of the matches using the list of parameters supported by it.

This post aims to explore the primary and advanced use of the PowerShell Select-String cmdlet.

How to use PowerShell select-string cmdlet

In PowerShell, the Select-String cmdlet can be used to search for a single pattern or multiple patterns in the file or string. The following syntax is used to refer Select-String cmdlet:

Select-String <Parameter>

The following parameters can be used with the Select-String cmdlet:

Pattern: Identifies the text to be selected in the file.
Path: Refers to the path of the file.
CaseSensitive: Used to match the terms by matching the letter case.
NotMatch: Utilized to get the result that does not contain the specified text\pattern.
AllMatches: specifies finding more than one match in each line of the file.

Example 1: To select the specific pattern (text) in a file

The sample code is as follows to select the pattern (i.e., text/string) in the “Sample100.csv” file. Firstly, the absolute path of the “Sample100.csv” is given after the “-Path” parameter. Afterwards, the pattern “Mark” is set using the parameter “-Pattern”:

Select-String -Path "C:\Users\powershell\Documents\Sample\Sample100.csv" -Pattern "Mark"

The pattern was “Mark” and it is observed that the Select-String has printed the line (along with the line number) that contains the “Mark” in it.

Example 2: To select the multiple patterns (text) in a file

You can select or find multiple patterns within the file. To do so, the text to be searched is provided after the “-Pattern” parameter. The following command searches for the “Mark” and “Peter” keywords inside the “Sample.csv” file:

Select-String -Path "C:\Users\powershell\Documents\Sample\Sample100.csv" -Pattern "Mark","Peter"

As you can see, those lines are printed that contain either Mark or Peter.

Example 3: To select only limited records of specified patterns (text) in a file

The Select-String cmdlet can be used to search for the specific pattern in a file, but only the limited number of instances would be searched. In the given-below example, the “.csv” file is being filtered for the pattern “Mark”. However, the limit is set to 2 using the “-First” parameter:

Select-String -Path "C:\Users\powershell\Documents\Sample\Sample100.csv" -Pattern "Mark" | Select-Object * -First 2

In the above output, the first two occurrences of the “Mark” keyword are displayed on the PowerShell terminal.

Example 4: To select the patterns in specified columns

The Select-String cmdlet can be utilized with the Select-Object to select match the pattern and return specific properties of the line containing those patterns. For this, the pattern matching is specified in the Select-String cmdlet, and the filters will be applied in the Select-Object.

In our case, the following example command exercises the “Select-String” cmdlet to match patterns “Peter” or “Phil” in a CSV file. This Select-String command is then piped with the Select-Object cmdlet to get the LineNumber, Pattern, FileName, and Line that contains the patterns Peter or Phil:

Select-String -Path "C:\Users\powershell\Documents\Sample\Sample100.csv" -Pattern "Peter","Phil" | Select-Object LineNumber, Pattern, FileName, Line

It is observed from the output that the LineNumber, Pattern, Filename, and Lines are printed that contain the patterns, Peter or Phil.

Example 5: To select the “case sensitive” patterns (text) in a file

You can match a pattern with “-CaseSensitive” parameter to consider the letter case as well. The example command searches for the lines that contain “PETER”:

Select-String -Path "C:\Users\powershell\Documents\Sample\Sample100.csv" -Pattern "PETER" -CaseSensitive

As you can see, only three records are printed that contain the PETER keyword.

Example 6: To select the unmatched patterns (text) in a file

With the help of the “-NotMatch” parameter, we can select only those records that do not match the specific keywords. In the following example, we have specified two patterns (“Mark” and “Peter”) in the -NotMatch parameter:

Select-String -Path "C:\Users\powershell\Documents\Sample\Sample100.csv" -Pattern "Mark","Peter" -NotMatch

As it can be seen in the above records, the record printed on the console neither contains “Mark” nor “Peter”.

Conclusion

In PowerShell, the PowerShell Select-String cmdlet is utilized to find the specified text/pattern in the file. The use of the Select-String command can be enhanced by utilizing different parameters (-NotMatch, -CaseSensitive) and properties (FileName, Line, Pattern). Moreover, you can extend the usage of the Select-String cmdlet by using it with Select-Object. You have learned the working of the Select-String cmdlet and its use cases in various scenarios.