How can I create directory tree in C Linux

Question

I want an easy way to create multiple directories in C   Linux    For example I want to save a file lola file in the directory     tmp a b c   but if the directories are not there I want them to be created automagically  A working example would be perfect

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So I need mkdirp   today  and found the solutions on this page overly complicated  Hence I wrote a fairly short snippet  that easily be copied in for others who stumble upon this thread an wonder why we need so many lines of code   mkdirp h   ifndef MKDIRP H  define MKDIRP H   include  lt sys stat h gt    define DEFAULT MODE      S IRWXU   S IRGRP    S IXGRP   S IROTH   S IXOTH      Utility function to create directory tree    bool mkdirp const char  path  mode t mode   DEFAULT MODE     endif    MKDIRP H   mkdirp cpp   include  lt errno h gt   bool mkdirp const char  path  mode t mode         const cast for hack   char  p   const cast lt char  gt  path         Do mkdir for each slash until end of string or error   while   p      0            Skip first character     p            Find first slash or end     while  p      0   amp  amp   p         p            Remember value from p     char v    p          Write end of string at p      p     0           Create folder from path to   0  inserted at p     if mkdir path  mode     -1  amp  amp  errno    EEXIST           p   v        return false                Restore path to it s former glory      p   v         return true      If you don t like const casting and temporarily modifying the string  just do a strdup   and free   it afterwards

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If you don t have C  17 yet and look for a platform agnostic solution  use ghc  filesystem  The header-ony code is compatible to C  17  in fact a backport  and easy to migrate later on

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It should be noted that starting from C  17 filesystem interface is part of the standard library  This means that one can have following to create directories    include  lt filesystem gt   std  filesystem  create directories   a b c d     More info here  https   en cppreference com w cpp filesystem create directory  Additionally  with gcc  one needs to  -std c  17  to CFLAGS  And  -lstdc  fs  to LDLIBS  The latter potentially is not going to be required in the future

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So many approaches has been described here but most of them need hard coding of your path into your code  There is an easy solution for that problem  using QDir and QFileInfo  two classes of Qt framework  Since your already in Linux environment it should be easy to use Qt   QString qStringFileName  path to the file that dont exist txt    QDir dir   QFileInfo qStringFileName  dir    if  dir exists              dir mkpath dir path         Make sure you have write access to that Path

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Since this post is ranking high in Google for  Create Directory Tree   I am going to post an answer that will work for Windows     this will work using Win32 API compiled for UNICODE or MBCS  This is ported from Mark s code above   Since this is Windows we are working with  directory separators are BACK-slashes  not forward slashes  If you would rather have forward slashes  change      to      It will work with   c  foo bar hello world   and  c  foo bar hellp world     i e   does not need trailing slash  so you don t have to check for it    Before saying  Just use SHCreateDirectoryEx   in Windows   note that SHCreateDirectoryEx   is deprecated and could be removed at any time from future versions of Windows   bool CreateDirectoryTree LPCTSTR szPathTree  LPSECURITY ATTRIBUTES lpSecurityAttributes   NULL       bool bSuccess   false      const BOOL bCD   CreateDirectory szPathTree  lpSecurityAttributes       DWORD dwLastError   0      if  bCD           dwLastError   GetLastError         else          return true            switch dwLastError           case ERROR ALREADY EXISTS              bSuccess   true              break          case ERROR PATH NOT FOUND                                TCHAR szPrev MAX PATH     0                   LPCTSTR szLast    tcsrchr szPathTree                         tcsnccpy szPrev szPathTree  int  szLast-szPathTree                    if CreateDirectoryTree szPrev lpSecurityAttributes                        bSuccess   CreateDirectory szPathTree lpSecurityAttributes   0                      if  bSuccess                           bSuccess    GetLastError    ERROR ALREADY EXISTS                                          else                      bSuccess   false                                              break          default              bSuccess   false              break             return bSuccess

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Easy with Boost Filesystem  create directories   include  lt boost filesystem hpp gt        boost  filesystem  create directories   tmp a b c      Returns  true if a new directory was created  otherwise false

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The others got you the right answer  but I thought I d demonstrate another neat thing you can do   mkdir -p  tmp a  b c  d   Will create the following paths    tmp a b d  tmp a c d   The braces allow you to create multiple directories at once on the same level of the hierarchy  whereas the -p option means  create parent directories as needed

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Here s C C   recursive function that makes use of dirname   to traverse bottom-up the directory tree  It will stop as soon as it finds an existing ancestor    include  lt libgen h gt   include  lt string h gt   int create dir tree recursive const char  path  const mode t mode        if  strcmp path          0     No need of checking if we are at root          return 0          Check whether this dir exists or not      struct stat st      if  stat path   amp st     0     S ISDIR st st mode                    Check and create parent dir tree first          char  path2   strdup path           char  parent dir path   dirname path2           if  create dir tree recursive parent dir path  mode     -1              return -1              Create this dir          if  mkdir path  mode     -1              return -1             return 0

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include  lt sys types h gt   include  lt sys stat h gt   int status      status   mkdir   tmp a b c   S IRWXU   S IRWXG   S IROTH   S IXOTH     From here   You may have to do separate mkdirs for  tmp   tmp a   tmp a b  and then  tmp a b c because there isn t an equivalent of the -p flag in the C api   Be sure and ignore the EEXISTS errno while you re doing the upper level ones

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This is similar to the previous but works forward through the string instead of recursively backwards   Leaves errno with the right value for last failure   If there s a leading slash  there s an extra time through the loop which could have been avoided via one find first of   outside the loop or by detecting the leading   and setting pre to 1   The efficiency is the same whether we get set up by a first loop or a pre loop call  and the complexity would be  slightly  higher when using the pre-loop call    include  lt iostream gt   include  lt string gt   include  lt sys stat h gt   int mkpath std  string s mode t mode        size t pos 0      std  string dir      int mdret       if s s size  -1                    force trailing   so we can handle everything in loop         s                  while  pos s find first of     pos    std  string  npos           dir s substr 0 pos             if dir size    0  continue     if leading   first time is 0 length         if  mdret mkdir dir c str   mode    amp  amp  errno  EEXIST               return mdret                      return mdret     int main         int mkdirretval      mkdirretval mkpath    foo bar  0755       std  cout  lt  lt  mkdirretval  lt  lt    n

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With C  17 or later  there s the standard header  lt filesystem gt  with function std  filesystem  create directories which should be used in modern C   programs  The C   standard functions do not have the POSIX-specific explicit permissions  mode  argument  though   However  here s a C function that can be compiled with C   compilers          File            mkpath c     Purpose         Create all directories in path     Author          J Leffler     Copyright        C  JLSS 1990-2020     Derivation      mkpath c 1 16 2020 06 19 15 08 10       TABSTOP 4     include  posixver h   include  mkpath h   include  emalloc h    include  lt errno h gt   include  lt string h gt      sysstat h      lt sys stat h gt  with fixup for  old  Windows - inc mode t     include  sysstat h   typedef struct stat Stat   static int do mkdir const char  path  mode t mode        Stat            st      int             status   0       if  stat path   amp st     0                   Directory does not exist  EEXIST for race condition            if  mkdir path  mode     0  amp  amp  errno    EEXIST              status   -1            else if   S ISDIR st st mode                 errno   ENOTDIR          status   -1             return status             mkpath - ensure all directories in path exist    Algorithm takes the pessimistic view and works top-down to ensure    each directory in path exists  rather than optimistically creating    the last element and working backwards     int mkpath const char  path  mode t mode        char            pp      char            sp      int             status      char            copypath   STRDUP path        status   0      pp   copypath      while  status    0  amp  amp   sp   strchr pp           0                if  sp    pp                           Neither root nor double slash in path                 sp     0               status   do mkdir copypath  mode                sp                          pp   sp   1            if  status    0          status   do mkdir path  mode       FREE copypath       return  status       ifdef TEST   include  lt stdio h gt   include  lt unistd h gt         Stress test with parallel running of mkpath   function     Before the EEXIST test  code would fail     With the EEXIST test  code does not fail        Test shell script    PREFIX mkpath       NAME    PREFIX sa 32 ad 13 23 13 12 13 sd ds ww qq ss dd zz xx dd rr ff ff ss ss ss ss ss ss ss ss        MKPATH  mkpath        MKPATH  NAME  amp         repeat a dozen times or so           MKPATH  NAME  amp     wait    rm -fr    PREFIX      int main int argc  char   argv        int             i       for  i   1  i  lt  argc  i                  for  int j   0  j  lt  20  j                          if  fork      0                                int rc   mkpath argv i   0777                   if  rc    0                      fprintf stderr    d  failed to create   d   s    s n                                int getpid    errno  strerror errno   argv i                    exit rc    0   EXIT SUCCESS   EXIT FAILURE                                   int status          int fail   0          while  wait  amp status     -1                        if  WEXITSTATUS status     0                  fail   1                    if  fail    0              printf  created   s n   argv i              return 0       endif    TEST      The macros STRDUP   and FREE   are error-checking versions of strdup   and free    declared in emalloc h  and implemented in emalloc c and estrdup c   The  sysstat h  header deals with broken versions of  lt sys stat h gt  and can be replaced by  lt sys stat h gt  on modern Unix systems  but there were many issues back in 1990   And  mkpath h  declares mkpath     The change between v1 12  original version of the answer  and v1 13  amended version of the answer  was the test for EEXIST in do mkdir    This was pointed out as necessary by Switch  mdash  thank you  Switch  The test code has been upgraded and reproduced the problem on a MacBook Pro  2 3GHz Intel Core i7  running Mac OS X 10 7 4   and suggests that the problem is fixed in the revision  but testing can only show the presence of bugs  never their absence   The code shown is now v1 16  there have been cosmetic or administrative changes made since v1 13  such as use mkpath h instead of jlss h and include  lt unistd h gt  unconditionally in the test code only   It s reasonable to argue that  sysstat h  should be replaced by  lt sys stat h gt  unless you have an unusually recalcitrant system    You are hereby given permission to use this code for any purpose with attribution    This code is available in my SOQ  Stack Overflow Questions  repository on GitHub as files mkpath c and mkpath h  etc   in the src so-0067-5039 sub-directory

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I know it s an old question but it shows up high on google search results and the answers provided here are not really in C   or are a bit too complicated   Please note that in my example createDirTree   is very simple because all the heavy lifting  error checking  path validation  needs to be done by createDir   anyway  Also createDir   should return true if directory already exists or the whole thing won t work   Here s how I would do that in C      include  lt iostream gt   include  lt string gt   bool createDir const std  string dir        std  cout  lt  lt   Make sure dir is a valid path  it does not exist and create it                   lt  lt  dir  lt  lt  std  endl      return true     bool createDirTree const std  string full path        size t pos   0      bool ret val   true       while ret val    true  amp  amp  pos    std  string  npos                pos   full path find      pos   1           ret val   createDir full path substr 0  pos               return ret val     int main         createDirTree   tmp a b c        return 0      Of course createDir   function will be system-specific and there are already enough examples in other answers how to write it for linux  so I decided to skip it

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Here is my example of code  it works for both Windows and Linux     include  lt iostream gt   include  lt string gt   include  lt sys stat h gt     stat  include  lt errno h gt        errno  ENOENT  EEXIST  if defined  WIN32   include  lt direct h gt        mkdir  endif  bool isDirExist const std  string amp  path     if defined  WIN32      struct  stat info      if   stat path c str     amp info     0                return false            return  info st mode  amp   S IFDIR     0   else      struct stat info      if  stat path c str     amp info     0                return false            return  info st mode  amp  S IFDIR     0   endif    bool makePath const std  string amp  path     if defined  WIN32      int ret    mkdir path c str      else     mode t mode   0755      int ret   mkdir path c str    mode    endif     if  ret    0          return true       switch  errno            case ENOENT             parent didn t exist  try to create it                       int pos   path find last of                   if  pos    std  string  npos   if defined  WIN32                  pos   path find last of                    if  pos    std  string  npos   endif                 return false              if   makePath  path substr 0  pos                     return false                       now  try to create again  if defined  WIN32          return 0     mkdir path c str      else          return 0    mkdir path c str    mode    endif      case EEXIST             done          return isDirExist path        default          return false           int main int argc  char  ARGV          for  int i 1  i lt argc  i                  std  cout  lt  lt   creating    lt  lt  ARGV i   lt  lt           lt  lt   makePath ARGV i      OK     failed    lt  lt  std  endl            return 0      Usage     makePath 1 2 folderA folderB folderC creating 1 2     OK creating folderA folderB folderC     OK

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You said  C    but everyone here seems to be thinking  Bash shell    Check out the source code to gnu mkdir  then you can see how to implement the shell commands in C

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bool mkpath  std  string path         bool bSuccess   false      int nRC     mkdir  path c str    0775        if  nRC    -1                 switch  errno                         case ENOENT                    parent didn t exist  try to create it                 if  mkpath  path substr 0  path find last of                                 Now  try to create again                      bSuccess   0      mkdir  path c str    0775                    else                     bSuccess   false                  break              case EEXIST                    Done                  bSuccess   true                  break              default                  bSuccess   false                  break                      else         bSuccess   true      return bSuccess

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If dir does not exist  create it   boost  filesystem  create directories boost  filesystem  path output file  parent path   string   c str

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system  mkdir -p  tmp a b c     is the shortest way I can think of  in terms of the length of code  not necessarily execution time     It s not cross-platform but will work under Linux

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mkdir -p  dir to the file  touch  dir to the file thefile ending

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