rh124_advanced_permissions

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rh124_advanced_permissions [2026/10/23 09:25] – [The setgid bit] rpjdayrh124_advanced_permissions [2026/10/28 14:01] (current) – [SGID bit for directories] rpjday
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 ====== RH124 Advanced Permissions ====== ====== RH124 Advanced Permissions ======
 +
 +===== NOTE =====
 +
 +If you're running these commands as a non-root user, do not use the ''sudo'' command.
 +
 +===== Enterable but not readable directories =====
 +
 +<code>
 +$ chmod 0111 Poems
 +$ ls -ld Poems
 +$ ls Poems
 +$ cat Poems/twister
 +$ chmod 755 Poems
 +</code>
  
 ===== Strange permissions ===== ===== Strange permissions =====
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 so a full octal representation for any file permissions would be octal 7777 (regular settings are sometimes written 0755 or 0644 or whatever). so a full octal representation for any file permissions would be octal 7777 (regular settings are sometimes written 0755 or 0644 or whatever).
  
-===== The setuid bit =====+===== The setuid bit for executable files =====
  
 This bit means that when you run this binary executable, it will **retain** its ownership: This bit means that when you run this binary executable, it will **retain** its ownership:
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 </code> </code>
  
-===== The setgid bit =====+===== The setgid bit for executable files =====
  
 No longer as popular but similar to above: No longer as popular but similar to above:
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 /sys/fs/bpf /sys/fs/bpf
 /tmp /tmp
-/tmp/.X11-unix +... snip ...
-/tmp/.ICE-unix +
-/tmp/.XIM-unix +
-/tmp/.font-unix +
-/tmp/systemd-private-f5f7d1e9279c4beebbdb24085e4c3d82-dbus-broker.service-rm2smd/tmp +
-/tmp/systemd-private-f5f7d1e9279c4beebbdb24085e4c3d82-chronyd.service-KYCF1b/tmp +
-/tmp/systemd-private-f5f7d1e9279c4beebbdb24085e4c3d82-irqbalance.service-Xglrdp/tmp +
-/tmp/systemd-private-f5f7d1e9279c4beebbdb24085e4c3d82-systemd-logind.service-dLohsJ/tmp +
-/var/tmp +
-/var/tmp/systemd-private-f5f7d1e9279c4beebbdb24085e4c3d82-dbus-broker.service-lkWgGX/tmp +
-/var/tmp/systemd-private-f5f7d1e9279c4beebbdb24085e4c3d82-chronyd.service-n9CB6t/tmp +
-/var/tmp/systemd-private-f5f7d1e9279c4beebbdb24085e4c3d82-irqbalance.service-WjxydR/tmp +
-/var/tmp/systemd-private-f5f7d1e9279c4beebbdb24085e4c3d82-systemd-logind.service-LeW18R/tmp+
 $ $
 </code> </code>
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 drwxrwxrwt. 2 root root 40 Oct 23 02:00 /dev/mqueue drwxrwxrwt. 2 root root 40 Oct 23 02:00 /dev/mqueue
 $ $
 +</code>
  
 Setting/unsetting the sticky bit: Setting/unsetting the sticky bit:
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 $ chmod -t <dirs> $ chmod -t <dirs>
 </code> </code>
 +
 +===== SGID bit for directories =====
 +
 +This identifies directories such that, when new files or directories are created within that directory, they take on the same group affiliation of the directory itself, regardless of who does the creation.
 +
 +<code>
 +$ find / -type d -perm -2000 2> /dev/null
 +</code>
 +
 +How to add to a directory:
 +
 +<code>
 +$ chmod g+s <directory name>
 +</code>
 +
 +**NOTE**: There is no value for the SUID bit on directories.
 +===== Ask Google =====
 +
 +Google: Does EX200 exam ask about setuid and setgid and sticky bit?
 +
 +//"Yes, the Red Hat Certified System Administrator (RHCSA EX200) exam does cover special permissions, including setuid, setgid, and the sticky bit."//
  
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  • Last modified: 2026/10/23 09:25
  • by rpjday