How does FOR work in cmd batch file

Question

I ve been programming in dozens of languages for 20 years but I could never understand how  FOR  work in windows cmd shell batch file  no matter how hard I tried   I read   http   www amazon com Windows-Administration-Command-Line-Vista dp 0470046163 ref sr 1 1 ie UTF8 amp s books amp qid 1241362727 amp sr 8-1  http   www ss64 com nt for html  and several other articles on the internet but still confuse and cannot accomplish anything   Can anybody give me a concise explaination on how  FOR  works in general    For a little more specific question  how can I iterate through each path in  PATH  variable   I ve tried with   rem showpathenv bat for  f  delims      g in    PATH    do echo   g   That d show only the first path  not all of them  Why   What I do wrong

User · Answer

for  f iterates per line input  so in your program will only output first path   your program treats  PATH  as one-line input  and deliminate  by    put first result to   g  then output   g  first deliminated path

User · Answer

Couldn t resist throwing this out there  old as this thread is     Usually when the need arises to iterate through each of the files in PATH  all you really want to do is find a particular file     If that s the case  this one-liner will spit out the first directory it finds your file in    ex   looking for java exe   for   x in  java exe  do echo    dp PATH x

User · Answer

I know this is SUPER old    but just for fun I decided to give this a try    Echo OFF setlocal set testpath  path      FOR  F  tokens   delims      P in    testpath    do call  loop   P  loop if   1      goto endloop set testpath  1 set testpath  testpath      echo  testpath  SHIFT goto  loop  endloop pause endlocal exit   This doesn t require a count and will go until it finishes  I had the same problem with spaces but it made it through the entire variable  The key to this is the loop labels and the SHIFT function

User · Answer

Here is a good guide   FOR  F - Loop command  against a set of files   FOR  F - Loop command  against the results of another command   FOR - Loop command  all options Files  Directory  List    The whole guide  Windows XP commands    http   www ss64 com nt index html  Edit  Sorry  didn t see that the link was already in the OP  as it appeared to me as a part of the Amazon link

User · Answer

Mark s idea was good  but maybe forgot some path have spaces in them   Replacing     with       instead would cut all paths into quoted strings   set  path   PATH         for   p in    path   do if not     p      echo    p   So here  you have your paths displayed   FOR command in cmd has a tedious learning curve  notably because how variables react within    s statements     you can assign any variables  but you can t read then back within the    s  unless you use the  setlocal ENABLEDELAYEDEXPANSION  statement  and therefore also use the variables with    s instead of    s    var    I currently exclusively script with cmd  for work  had to learn all this

User · Answer

This works for me     ECHO OFF SETLOCAL ENABLEDELAYEDEXPANSION ENABLEEXTENSIONS  REM insure path is terminated with a   set tpath  path   echo   again  REM This FOR statement grabs the first element in the path FOR  F  delims      I IN    TPATH    DO     echo      I     REM remove the current element of the path   set TPATH  TPATH   I       REM loop back if there is more to do   IF DEFINED TPATH GOTO  again  ENDLOCAL

User · Answer

It works for me  try it   for  f  tokens   delims     g in   echo  PATH    do echo  g

User · Answer

FOR is essentially iterating over the  lines  in the data set  In this case  there is one line that contains the path  The  delims    is just telling it to separate on semi-colons  If you change the body to echo   g   h   i   j   k you ll see that it is treating the input as a single line and breaking it into multiple tokens

User · Answer

You ve got the right idea  but for  f is designed to work on multi-line files or commands  not individual strings   In its simplest form  for is like Perl s for  or every other language s foreach   You pass it a list of tokens  and it iterates over them  calling the same command each time   for  a in  hello world  do  echo  a   The extensions merely provide automatic ways of building the list of tokens   The reason your current code is coming up with nothing is that     is the default end of line  comment  symbol   But even if you change that  you d have to use   g    h    i      to access the individual tokens  which will severely limit your batch file   The closest you can get to what you ask for is   set TabbedPath  PATH      for   g in   TabbedPath   do echo   g   But that will fail for quoted paths that contain semicolons   In my experience  for  l and for  r are good for extending existing commands  but otherwise for is extremely limited   You can make it slightly more powerful  and confusing  with delayed variable expansion  cmd  v on   but it s really only good for lists of filenames   I d suggest using WSH or PowerShell if you need to perform string manipulation   If you re trying to write whereis for Windows  try where

User · Answer

You have to additionally use the tokens 1 2     part of the options that the for loop allows  This here will do what you possibly want   for  f  tokens 1 2 3 4 5 6 7 8 9 10 11 12 delims     a in    PATH      do          echo   b       amp  echo   a       amp  echo   c       amp  echo   d       amp  echo   e       amp  echo   f       amp  echo   g       amp  echo   h       amp  echo   i       amp  echo   j       amp  echo   k       amp  echo        amp  echo       and now for some more          amp  echo        amp  echo   a     b      c      d       amp  dir   e        amp  cd   f        amp  dir  tw   g        amp  echo    h   i   j   k        amp  cacls   f     This example processes the first 12 tokens   directories from  path   only  It uses explicit enumeration of each of the used tokens  Note  that the token names are case sensitive   a is different from  A   To be save for paths with spaces  surround all  x with quotes like this   i   I didn t do it here where I m only echoing the tokens   You could also do s th  like this   for  f  tokens 1 3 5 7-26  delims     a in    PATH      do          echo   c       amp  echo   b       amp  echo   a       amp  echo   d       amp  echo   e       amp  echo   f       amp  echo   g       amp  echo   h       amp  echo   i       amp  echo   j       amp  echo   k     This one skips tokens 2 4 6 and uses a little shortcut   7-26   to name the rest of them  Note how  c   b   a are processed in reverse order this time  and how they now  mean  different tokens  compared to the first example   So this surely isn t the concise explanation you asked for  But maybe the examples help to clarify a little better now

User · Answer

It works for me  try it   for  f  delims     g in   echo  PATH    do echo  g

User · Answer

None of the answers actually work  I ve managed to find the solution myself  This is a bit hackish  but it solve the problem for me   echo off setlocal enableextensions setlocal enabledelayedexpansion set MAX TRIES 100 set P  PATH  for  L   a in  1  1   MAX TRIES   do     for  F  delims      g in    P    do       echo   g     set P  P   g        if   P         g  goto  eof         Oh   I hate batch file programming     Updated  Mark s solution is simpler but it won t work with path containing whitespace  This is a little-modified version of Mark s solution  echo off setlocal enabledelayedexpansion set NonBlankPath  PATH      set TabbedPath  NonBlankPath      for   g in   TabbedPath   do     set GG   g   echo  GG

[batch-file] How does "FOR" work in cmd batch file?

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