是否在功能上等效于使用“ tokens = *”或“ delims =”调用FOR？

Question

Consider the following two loops:

for /f "tokens=*" %%a in ('dir /b %TEMP%') do (
   echo %%a
)

and

for /f "delims=" %%a in ('dir /b %TEMP%') do (
   echo %%a
)

If my desired result is to provide the variable %%a with the contents of the entire line being evaluated, are the options tokens=* and delims= functionally equivalent?

Are there any situations where I might get a different output with one or the other given a particular input?

I would like to know if these two options should always be used in combination to guarantee coverage of all potential cases or if specifying both is redundant.

Answer 1

Yes, tokens=* and delims= are different:

• delims= returns the whole line unedited;
• tokens=* returns the line with any leading delimiters ( SPACE and TAB as per default) removed;
• tokens=* delims= behaves exactly the same way as delims= ;

Note that empty lines are always skipped. Also lines that begin with ; are ignored as that character is the default eol .

If tokens=* is specified and a line contains delimiters only, the for /F loop iterates and the meta variable returns an empty string. As soon as any token number is provided (like tokens=3 , tokens=1,3 , tokens=2-3 , tokens=2* , etc.), delimiter-only lines are skipped.
However, a line that contains one or more delimiters plus the eol character plus an arbitrary string are ignored even when tokens=* is provided.

---

For evidence I did some tests, using the following text file sample.txt (note that the 2 ^nd line is empty, the 4 ^th line contains four SPACEs ; click on the edit button below this answer and view the raw text):

 text_without_delimiters text with delimiters text with leading and trailing delimiters ; comment text ; comment text with leading delimiters text plus ; comment text 

And here is what I did on the console together with the respective return strings:

>>> for /F %I in (sample.txt) do @echo "%I"
"text_without_delimiters"
"text"
"text"
"text"

>>> for /F "tokens=*" %I in (sample.txt) do @echo "%I"
"text_without_delimiters"
"text with delimiters"
""
"text with leading and trailing delimiters  "
"text plus ; comment text"

>>> for /F "delims=" %I in (sample.txt) do @echo "%I"
"text_without_delimiters"
"text with delimiters"
"    "
"  text with leading and trailing delimiters  "
"  ; comment text with leading delimiters"
"text plus ; comment text"

>>> for /F "tokens=* delims=" %I in (sample.txt) do @echo "%I"
"text_without_delimiters"
"text with delimiters"
"    "
"  text with leading and trailing delimiters  "
"  ; comment text with leading delimiters"
"text plus ; comment text"

>>> for /F "tokens=3" %I in (sample.txt) do @echo "%I"
"delimiters"
"leading"
";"

>>> for /F "tokens=1,3" %I in (sample.txt) do @echo "%I"    "%J"
"text_without_delimiters"    ""
"text"    "delimiters"
"text"    "leading"
"text"    ";"

>>> for /F "tokens=2-3" %I in (sample.txt) do @echo "%I"    "%J"
"with"    "delimiters"
"with"    "leading"
"plus"    ";"

>>> for /F "tokens=2*" %I in (sample.txt) do @echo "%I"    "%J"
"with"    "delimiters"
"with"    "leading and trailing delimiters  "
"plus"    "; comment text"

So the only really strange and unexpected output is the line "" with the tokens=* option alone.