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--- linux_wiki:file_system_hierarchy [2015/11/16 22:34]
billdozor created
+++ linux_wiki:file_system_hierarchy [2016/05/09 22:38]
billdozor [Top Level Directories]
@@ Line 4: / Line 4: @@
 Some of the most common top level directories in the Linux file system.
+**Checklist**
+  * Distro(s): Any
 **Sources**
@@ Line 12: / Line 15: @@
 ====== Top Level Directories ======
+EL7 = Enterprise Linux 7 (Red Hat, CentOS, Scientific)
 ^  Directory  ^  Used For  ^
 |  /  | Root directory; file system tree starts here |
-|  /bin  | Executable programs needed to repair system; essential during boot |
+|  /bin  | Executable programs needed to repair system; essential during boot; \\ EL7 symlinks /bin -> /usr/bin |
 |  /boot  | All files needed to boot the Linux kernel |
 |  /dev  | Special/device files; refer to physical device  |
 |  /etc  | "etcetera"; configuration files local to the system |
 |  /home  | User local home directories |
-|  /lib and /lib64  | Shared libraries used by programs in /boot,/bin, /sbin |
+|  /lib and /lib64  | Shared libraries used by programs in /boot,/bin, /sbin; \\ EL7 symlinks /lib -> /usr/lib and /lib64 -> /usr/lib64 |
 |  /media and /mnt  | Mount points for removable media and temporary file systems respectively  |
 |  /opt  | Add on or optional packages |
@@ Line 26: / Line 31: @@
 |  /root  | Home directory for the root user |
 |  /run  | Process/user specific info created since last boot |
-|  /sbin  | Similar to /bin, except for system administration not used by regular users |
+|  /sbin  | Similar to /bin, except for system administration not used by regular users; \\ EL7 symlinks /sbin -> /usr/sbin |
 |  /srv  | Directory to use for data used by services (such as NFS, FTP, HTTP) |
 |  /sys  | To interface with hardware devices managed by the kernel |
 |  /tmp  | Temporary files that could be deleted without warning during boot |
-|  /usr  | Directory containing sub directories with program files, libraries, and documentation. Typically mimics the contents of /. Not required during boot. |
+|  /usr  | Directory containing sub directories with program files, libraries, and documentation. Typically mimics the contents of /. EL6: Not required during boot. EL7: Important directory contents has been relocated here; now required during boot. |
 |  /var  | Files that can change dynamically (log files, mail, and spool files) |
@@ Line 37: / Line 42: @@
 ====== Common Directories with Own Partition ======
-It is common to separate the following directories onto their own mount point/partition:
+It is common to mount the following directories onto their own partition:
-  * / => isolate the core OS away from the rest of the system.
+^  Directory  ^ Reason ^
-  * /boot => isolate kernel boot images, cannot be LVM.
+|  /  | isolate the core OS away from the rest of the system |
-  * /home => in order to isolate user data from the rest of the system.
+|  /boot  | isolate kernel boot images, cannot be LVM |
-  * /tmp => isolate world writeable /tmp to give more secure mount options.
+|  /home  | isolate user data from the rest of the system; usually to allocate more storage space and preserve user data during upgrades |
-  * /var => isolate other variable data that could grow from affecting the rest of the system. (yum cache, common place for applications to write to)
+|  /tmp  | isolate world writeable /tmp to give more secure mount options |
-  * /var/log => prevent run away log files from affecting the rest of the system.
+|  /var  | isolate other variable data that could grow from affecting the rest of the system. (yum cache, common place for applications to write to) |
+|  /var/log  | prevent run away log files from affecting the rest of the system |
 ----
+====== View Mounts ======
+Different ways to see file system mounts.
+----
+===== Find Mounts =====
+The "findmnt" command shows a tree like mount structure.
+<code bash>
+[root@srv01 ~]# findmnt
+TARGET                           SOURCE                                FSTYPE     OPTIONS
+/                                /dev/mapper/vgroot-lvroot             xfs        rw,relatime,attr2,inode64,noquota
+├─/proc                          proc                                  proc       rw,nosuid,nodev,noexec,relatime
+│ └─/proc/sys/fs/binfmt_misc     systemd-1                             autofs     rw,relatime,fd=40,pgrp=1,timeout=300,minproto=5,maxproto=5,direct
+├─/sys                           sysfs                                 sysfs      rw,nosuid,nodev,noexec,relatime
+│ ├─/sys/kernel/security         securityfs                            securityfs rw,nosuid,nodev,noexec,relatime
+│ ├─/sys/fs/cgroup               tmpfs                                 tmpfs      rw,nosuid,nodev,noexec,mode=755
+│ │ ├─/sys/fs/cgroup/systemd     cgroup                                cgroup     rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd
+│ │ ├─/sys/fs/cgroup/cpuset      cgroup                                cgroup     rw,nosuid,nodev,noexec,relatime,cpuset
+│ │ ├─/sys/fs/cgroup/cpu,cpuacct cgroup                                cgroup     rw,nosuid,nodev,noexec,relatime,cpuacct,cpu
+│ │ ├─/sys/fs/cgroup/memory      cgroup                                cgroup     rw,nosuid,nodev,noexec,relatime,memory
+│ │ ├─/sys/fs/cgroup/devices     cgroup                                cgroup     rw,nosuid,nodev,noexec,relatime,devices
+│ │ ├─/sys/fs/cgroup/freezer     cgroup                                cgroup     rw,nosuid,nodev,noexec,relatime,freezer
+│ │ ├─/sys/fs/cgroup/net_cls     cgroup                                cgroup     rw,nosuid,nodev,noexec,relatime,net_cls
+│ │ ├─/sys/fs/cgroup/blkio       cgroup                                cgroup     rw,nosuid,nodev,noexec,relatime,blkio
+│ │ ├─/sys/fs/cgroup/perf_event  cgroup                                cgroup     rw,nosuid,nodev,noexec,relatime,perf_event
+│ │ └─/sys/fs/cgroup/hugetlb     cgroup                                cgroup     rw,nosuid,nodev,noexec,relatime,hugetlb
+│ ├─/sys/fs/pstore               pstore                                pstore     rw,nosuid,nodev,noexec,relatime
+│ ├─/sys/kernel/config           configfs                              configfs   rw,relatime
+│ └─/sys/kernel/debug            debugfs                               debugfs    rw,relatime
+├─/dev                           devtmpfs                              devtmpfs   rw,nosuid,size=1829904k,nr_inodes=457476,mode=755
+│ ├─/dev/shm                     tmpfs                                 tmpfs      rw,nosuid,nodev
+│ ├─/dev/pts                     devpts                                devpts     rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000
+│ ├─/dev/mqueue                  mqueue                                mqueue     rw,relatime
+│ └─/dev/hugepages               hugetlbfs                             hugetlbfs  rw,relatime
+├─/run                           tmpfs                                 tmpfs      rw,nosuid,nodev,mode=755
+├─/mnt/redusb                    /dev/mapper/vgredusb-lvredbackups     ext4       rw,relatime,data=ordered
+├─/mnt/blackusb                  /dev/mapper/vgblackusb-lvblackbackups ext4       rw,relatime,data=ordered
+├─/boot                          /dev/sda1                             xfs        rw,relatime,attr2,inode64,noquota
+├─/tmp                           /dev/mapper/vgroot-lvtmp              xfs        rw,relatime,attr2,inode64,noquota
+├─/home                          /dev/mapper/vgroot-lvhome             xfs        rw,relatime,attr2,inode64,noquota
+└─/var                           /dev/mapper/vgroot-lvvar              xfs        rw,relatime,attr2,inode64,noquota
+</code>
+----
+===== Mount =====
+The "mount" command showing only xfs and ext4 file system types (-t xfs,ext4)
+<code bash>
+[root@srv01 ~]# mount -t xfs,ext4
+/dev/mapper/vgroot-lvroot on / type xfs (rw,relatime,attr2,inode64,noquota)
+/dev/mapper/vgblackusb-lvblackbackups on /mnt/blackusb type ext4 (rw,relatime,data=ordered)
+/dev/mapper/vgredusb-lvredbackups on /mnt/redusb type ext4 (rw,relatime,data=ordered)
+/dev/mapper/vgroot-lvtmp on /tmp type xfs (rw,relatime,attr2,inode64,noquota)
+/dev/mapper/vgroot-lvhome on /home type xfs (rw,relatime,attr2,inode64,noquota)
+/dev/mapper/vgroot-lvvar on /var type xfs (rw,relatime,attr2,inode64,noquota)
+/dev/sda1 on /boot type xfs (rw,relatime,attr2,inode64,noquota)
+</code>
+----
+===== df =====
+"df" command with human readable (-h) and print file system type (-T):
+<code bash>
+[root@srv01 ~]# df -hT
+Filesystem                            Type      Size  Used Avail Use% Mounted on
+/dev/mapper/vgroot-lvroot             xfs        30G  1.9G   29G   7% /
+devtmpfs                              devtmpfs  1.8G     0  1.8G   0% /dev
+tmpfs                                 tmpfs     1.8G     0  1.8G   0% /dev/shm
+tmpfs                                 tmpfs     1.8G  8.6M  1.8G   1% /run
+tmpfs                                 tmpfs     1.8G     0  1.8G   0% /sys/fs/cgroup
+/dev/mapper/vgblackusb-lvblackbackups ext4       99G   65G   29G  70% /mnt/blackusb
+/dev/mapper/vgredusb-lvredbackups     ext4       99G   66G   28G  71% /mnt/redusb
+/dev/mapper/vgroot-lvtmp              xfs       8.0G   33M  8.0G   1% /tmp
+/dev/mapper/vgroot-lvhome             xfs       100G   65G   36G  65% /home
+/dev/mapper/vgroot-lvvar              xfs       8.0G  527M  7.5G   7% /var
+/dev/sda1                             xfs       247M  164M   83M  67% /boot
+</code>