Find specified text within one or more files. More information: https://learn.microsoft.com/windows-server/administration/windows-commands/findstr.
findstr "string1 string2 ..." *
dir | findstr "string1 string2 ..."
findstr /s "string1 string2 ..." *
findstr /i "string1 string2 ..." *
findstr /r "expression" *
findstr /c:"string1 string2 ..." *.txt
findstr /n "string1 string2 ..." *
findstr /m "string1 string2 ..." *