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Voorbeeld: sudo chmod -R 705 /var/www/site


Met chmod pas je de file mode bits aan van bestanden. In deze context is een map ook een bestand. Aspecten die hierbij een rol spelen:

  • modes aka. rechten
  • Gebruikersgroeps
  • Representaties: Symbolisch of octaal
  • Manier van uitvoeren: Absoluut of differentiëel


* Read       - r
* Write      - w
* Execute    - x - Heeft betrekking op zowel bestanden als mappen
* Execute    - X - Heeft betrekking op alleen mappen
* Set ID     - s - Set user or group ID upon execution
* Sticky bit - t

Gebruikersgroeps (users)

* Eigenaar - u (user) - Bit 7-9 (bits 2-4 vanaf links)
* Groep    - g (group)
* Overig   - o (other)
* All      - a (all)   - Alledrie de groepen bij elkaar

Maak alleen mappen executeerbaar

Als derden (bv. Apache) een map moet kunnen benaderen (=cd), dan moet die map executeerbaar zijn. Bestanden wil je daarintegen vaak juist niet executeerbaar maken. Daar is een oplossing voor [1]:

chmod -R a+rX *

Dit zet de rechten van alle bestanden en mappen op a+r. Daarnaast worden alleen mappen executeerbaar gemaakt (vandaar de hoofdletter 'X').

Recursie & mappen


find /var/www -type d

krijg je een lijst terug met alle mappen. Daar kunnen spaties in zitten.


find /var/www/ -type d -exec chmod +x {} \;

maak je al deze mappen executeerbaar.

Overigens kan dit vermoedelijk eenvoudiger met

chmod -R +X /var/www/

Recursie & bestanden


find /var/www/sterk.dvb -type f

krijg je een recursieve lijst met alle bestanden. Daar kunnen spaties e.d. in zitten.

Met bv.

find /var/www/sterk.dvb -type f -exec chmod -x {} \;

worden alle bestanden niet-executeerbaar gemaakt.

Zie ook


Appendix: man chmod

CHMOD(1)                                        User Commands                                       CHMOD(1)

       chmod - change file mode bits

       chmod [OPTION]... MODE[,MODE]... FILE...
       chmod [OPTION]... OCTAL-MODE FILE...
       chmod [OPTION]... --reference=RFILE FILE...

       This  manual page documents the GNU version of chmod.  chmod changes the file mode bits of each given
       file according to mode, which can be either a symbolic representation of changes to make, or an octal
       number representing the bit pattern for the new mode bits.

       The  format  of  a symbolic mode is [ugoa...][[+-=][perms...]...], where perms is either zero or more
       letters from the set rwxXst, or a single letter from the set ugo.  Multiple  symbolic  modes  can  be
       given, separated by commas.

       A  combination of the letters ugoa controls which users' access to the file will be changed: the user
       who owns it (u), other users in the file's group (g), other users not in the file's group (o), or all
       users  (a).   If  none of these are given, the effect is as if a were given, but bits that are set in
       the umask are not affected.

       The operator + causes the selected file mode bits to be added to the existing file mode bits of  each
       file;  -  causes  them to be removed; and = causes them to be added and causes unmentioned bits to be
       removed except that a directory's unmentioned set user and group ID bits are not affected.

       The letters rwxXst select file mode bits for the affected users: read (r),  write  (w),  execute  (or
       search  for  directories)  (x), execute/search only if the file is a directory or already has execute
       permission for some user (X), set user or group ID on execution  (s),  restricted  deletion  flag  or
       sticky  bit (t).  Instead of one or more of these letters, you can specify exactly one of the letters
       ugo: the permissions granted to the user who owns the file (u),  the  permissions  granted  to  other
       users  who are members of the file's group (g), and the permissions granted to users that are in nei‐
       ther of the two preceding categories (o).

       A numeric mode is from one to four octal digits (0-7), derived by adding up the bits with  values  4,
       2,  and  1.  Omitted digits are assumed to be leading zeros.  The first digit selects the set user ID
       (4) and set group ID (2) and restricted deletion or sticky (1) attributes.  The second digit  selects
       permissions  for  the user who owns the file: read (4), write (2), and execute (1); the third selects
       permissions for other users in the file's group, with the same values; and the fourth for other users
       not in the file's group, with the same values.

       chmod never changes the permissions of symbolic links; the chmod system call cannot change their per‐
       missions.  This is not a problem since the permissions of symbolic links are  never  used.   However,
       for  each  symbolic  link listed on the command line, chmod changes the permissions of the pointed-to
       file.  In contrast, chmod ignores symbolic links encountered during recursive directory traversals.

       chmod clears the set-group-ID bit of a regular file if the file's group ID does not match the  user's
       effective  group  ID  or  one  of the user's supplementary group IDs, unless the user has appropriate
       privileges.  Additional restrictions may cause the set-user-ID and set-group-ID bits of MODE or RFILE
       to  be ignored.  This behavior depends on the policy and functionality of the underlying chmod system
       call.  When in doubt, check the underlying system behavior.

       chmod preserves a directory's set-user-ID and set-group-ID bits unless you explicitly specify  other‐
       wise.   You  can set or clear the bits with symbolic modes like u+s and g-s, and you can set (but not
       clear) the bits with a numeric mode.

       The restricted deletion flag or sticky bit is a single bit, whose interpretation depends on the  file
       type.  For directories, it prevents unprivileged users from removing or renaming a file in the direc‐
       tory unless they own the file or the directory; this is called the restricted deletion flag  for  the
       directory,  and is commonly found on world-writable directories like /tmp.  For regular files on some
       older systems, the bit saves the program's text image on the swap device so it will load more quickly
       when run; this is called the sticky bit.

       Change the mode of each FILE to MODE.

       -c, --changes
              like verbose but report only when a change is made

              do not treat `/' specially (the default)

              fail to operate recursively on `/'

       -f, --silent, --quiet
              suppress most error messages

       -v, --verbose
              output a diagnostic for every file processed

              use RFILE's mode instead of MODE values

       -R, --recursive
              change files and directories recursively

       --help display this help and exit

              output version information and exit

       Each MODE is of the form `[ugoa]*([-+=]([rwxXst]*|[ugo]))+'.

       Written by David MacKenzie and Jim Meyering.

       Report chmod bugs to
       GNU coreutils home page: <>
       General help using GNU software: <>
       Report chmod translation bugs to <>

       Copyright  ©  2011  Free  Software  Foundation,  Inc.   License  GPLv3+:  GNU  GPL version 3 or later
       This is free software: you are free to change and redistribute it.  There  is  NO  WARRANTY,  to  the
       extent permitted by law.


       The  full  documentation for chmod is maintained as a Texinfo manual.  If the info and chmod programs
       are properly installed at your site, the command

              info coreutils 'chmod invocation'

       should give you access to the complete manual.

GNU coreutils 8.12.197-032bb                   September 2011                                       CHMOD(1)