Chmod

Uvod Chmod je standradna UNIX naredba kojom određujemo prava pristupa određenoj datoteci ili određenom direktoriju.Poznavajući korištenje naredbe chmod u mogučnosti smo konfigurirati vrlo siguran sustav, u kojem će se točno znati koji korisnici smiju čitati, koji pisati, a koji izvršavati određene datoteke i direktorije.Ukoliko su pravila pristupa loše postavljena vrlo je vjerojatno da aplikacije koje zahtjevaju odredena prava pristupa nece dobro raditi, a i sam sustav je vrlo nesiguran.Upravo iz tih razloga osnovna pravila čitanja,pisanja i izvršavanja inicijalno su postavljena u svakoj Linux distribuciji, a mi ih po zelji mozemo modificirati upravo sa chmod naredbom

Argumenti chmod naredbe

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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.  Multi-
      ple symbolic modes can be given, separated by commas.

Simbolički oblik chmod naredbe je

Test title chmod [ugoa...][[+-=][perms...]...]

      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 let-
      ters, 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 neither  of  the
      two preceding categories (o).