Searches for regular expressions or text strings in files. Similar to grep on Unix, but is much more limited in the regular expressions it supports.

Treats space in a regular expression as a disjunction AKA logical or unless prevented with /c option.

Examples:

• findstr /s "[0-9][0-9].*[0-9][0-9]" *.h *.cpp

  Searches recursively all files whose name ends with .h or .cpp, printing only lines that contain two consecutive decimal digits followed by anything followed by two consecutive decimal digits.

• findstr "a.*b a.*c" File.txt

  Outputs all lines in File.txt that match any of the  two regular expressions separated by the space. Thus, the effect is one of  logical or on regular expressions.

• echo world | findstr "hello wo.ld"

  • Does not match. Since the 1st item before the space does not look like a regex, findstr treats the whole search term as a plain search term.

• echo world | findstr /r "hello wo.ld"

  Matches. The use of /r forces regex treatment.

• findstr /r /c:"ID: *[0-9]*" File.txt

  Outputs all lines in File.txt that match the single regular expression containing a space. The use of /c prevents the space from being treated as a logical or. The use of /r switches the regular expression treatment on, which was disabled by default by the use of /c. To test this, try the following:

  • echo ID: 12|findstr /r /c:"ID: *[0-9]*$"

    Matches.

  • echo ID: 12|findstr /c:"ID: *[0-9]*$"

    Does not match, as the search string is not interpreted as a regular expression.

  • echo ID: abc|findstr "ID: *[0-9]*$"

    Matches despite the output of echo failing to match the complete regular expression: the search is interpreted as one for lines matching ID: or *[0-9]*$.

• findstr /ric:"id: *[0-9]*" File.txt

  Does the same as the previous example, but in a case-insensitive manner.

  While findstr enables this sort of accumulation of switches behind a single /, this is not possible with any command. For instance, dir /bs does not work, while dir /b /s does.

  To test this, try the following:

  • echo ID: 12|findstr /ric:"id: *[0-9]*$"
  • echo ID: ab|findstr /ric:"id: *[0-9]*$"

• findstr /msric:"id: *[0-9]*" *.txt

  Like above, but recursively for all files per /s, displaying only matching files rather than matching lines per /m.

• echo hel lo | findstr /c:"hel lo" /c:world

  /c switch can be used multiple times to create logical or.

• echo \\hello\\ | findstr "\\hello\\"

  Does not match. Backslash before quotation marks and multiple other characters acts as an escape; thus, \" matches ".

• echo \\hello\\ | findstr "\\\\hello\\\\"

  Matches. Double backslash passed to findstr stands for a single backslash.

• echo \\hello\\ | findstr \\hello\\

  Matches. None of the single backslashes passed to findstr is followed by a character on which the backslash acts as an escape.

• echo ^"hey | findstr \\^"hey | more

  To search for a quote (quotation mark), you need to escape it two times: once for the shell using caret (^), and once for findstr using backslash (\\).

• echo ^"hey | findstr ^"\\^"hey there^" | more

  To search for a quote and have the search term enclosed in quotes as well, the enclosing quotes need to be escaped for the shell using caret (^).

• echo //comment line | findstr \\//