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--- bash:ls:ls_output_fields_definitions [2020/04/29 11:39] – peter
+++ bash:ls:ls_output_fields_definitions [2021/01/26 16:01] (current) – removed peter
@@ Line 1: / Line 1: @@
-====== BASH - ls - ls output fields definitions ======
-The output of the **ls** command depends on the version of "ls", the options used, the platform used, etc.
-<code bash>
-ls -al
-</code>
-returns:
-<code bash>
--rwxrw-r--    10    root   root 2048    Jan 13 07:11 afile.exe
-</code>
-----
-<code bash>
--rwxrw-r--    10    root   root 2048    Jan 13 07:11 afile.exe
-?UUUGGGOOOS   00  UUUUUU GGGGGG ####    ^             ^-- File name.
-^ ^  ^  ^ ^    ^      ^      ^    ^     \-- Date Time stamp.
-| |  |  | |    |      |      |    \--- File Size.
-| |  |  | |    |      |      \-------- Group Name (for example, Users, Administrators, etc).
-| |  |  | |    |      \--------------- Owner Name.
-| |  |  | |    \---------------------- Link count (Usually refers to number of hard links; but can vary.)
-| |  |  | \--------------------------- Alternative Access (blank means none defined, anything else varies)
-| \--\--\----------------------------- File Mode Permissions.  Read, Write and Special access modes for [U]ser, [G]roup, and [O]thers (everyone else).
-\------------------------------------- File Type flag.
-</code>
-  * **File Type flag**:  The very first character. Typically one of: **d** for directory, **l** for a symbolic link (hard links show normally without a special character of their own), or **-** for a normal file.
-      * There are many others, but less commonly seen, file types for various filesystems.  These first ten characters (file type and permissions) are discussed on [[https://en.wikipedia.org/wiki/File_system_permissions#Notation_of_traditional_Unix_permissions|Wikipedia]].  Again, your documentation will tell you exactly what kind of file types your command supports and displays.
-  * **File Mode Permissions**:   Three sets of three chars, where:
-      * First set is permissions for the "User" (i.e., Owner)
-      * Second set is permissions for the "Group"
-      * Third set is permissions for "Others" (i.e., everyone else; anyone who is neither Owner nor Group).
-  * **Link count**:  For files it means number of hard links.  For directories, its the number of directories inside the directory + this directory itself.
-  * **Alternative Access flag**:  Usually a blank space, but on some platforms, it may be used to indicate there are special/alternative access modes (such as ACLs and security descriptors on WIN32, etc), and varies widely – consult your manual, man pages, info tool, or what-not.
-  * **File Size**:  Some versions and/or command line flags will list the number of blocks used instead of the number of bytes; a filesystem with a block size of 1024 bytes will list all sizes up to 1024 bytes as "1", meaning 1 block is used, from 1025 to 2048 as "2", using 2 blocks, and so on.  But listing block sizes by default (without explicitly using a command line option) is rare on most modern un*x machines.
-  * **Date Time stamp**:  Usually the date/time the file was last modified, not the time the file was created.
-<WRAP info>
-**NOTE:**  If you cannot find a man/info page for **ls** itself (**man ls** / **info ls**), try looking in the **coreutils** package (**info coreutils**).
-Also note that among the more common platforms, Microsoft platforms tend not to translate very well to **ls** output, so you may see odd behavior, flags, or other unusual info in the output, depending on how your version of "ls" was compiled, what it was linked against, etc.
-</WRAP>
-----
-===== File Types flag =====
-On most systems, the first field is also used to indicate the presence of extra attributes like ACLs, security attributes or other extended attributes.
-|-|Regular file|
-|b|Block special file|
-|c|Character special file|
-|C|High performance ("contiguous data") file|
-|d|Directory|
-|D|Door (Solaris 2.5 and up)|
-|l|Symbolic link|
-|M|Off-line ("migrated") file (Cray DMF)|
-|n|Network special file (HP-UX)|
-|p|FIFO (named pipe)|
-|P|Port (Solaris 10 and up)|
-|s|Socket|
-|?|Some other file type|
-----
-===== File Mode Permissions =====
-Each of the three characters represent the read, write, and execute permissions:
-Usually in the form:
-<code>
-rwx rwx rwx
-</code>
-  * First set of rwx are permissions for the owner of the file.
-  * Second set of rwx are permissions for the group that the owner belongs to.  Everyone in the same group will get these permissions to the file.
-  * Third set of rwx are permissions for others.  That are not the owner; nor part of the group the owner is part of.
-|r|Reading is permitted.|
-|w|Writing is permitted.|
-|x|Execution is permitted.  For directories it means you can attempt to access the directory contents.|
-|-|The specific permission is not allowed.|
-but **ls** can combine multiple bits into the third character of each set of permissions as follows:
-|s|If the set-user-ID or set-group-ID bit and the corresponding executable bit are both set.|
-|S|If the set-user-ID or set-group-ID bit is set but the corresponding executable bit is not set.|
-|t|If the restricted deletion flag or sticky bit, and the other-executable bit, are both set.  The restricted deletion flag is another name for the sticky bit.|
-|T|If the restricted deletion flag or sticky bit is set but the other-executable bit is not set.|
-|x|If the executable bit is set and none of the above apply.|
-<WRAP info>
-**NOTE:** Sometimes you may encounter an **s** or **S** for setuid and/or setgid programs, or other less common characters.
-See your **ls** documentation for the mode characters it will show.
-</WRAP>
-----
-===== Alternative Access Types =====
-----
-===== Links =====
-Some platforms have an odd notion of what constitutes a **link**.
-These usually include hard links and symbolic links, as well as directory entries (which is why directories often have high link counts – its parent has one link, the directory has a link to itself in the . entry, and each of its sub-directories has a link back via ..
-----
-===== Date Time stamp =====
-The **Date Time stamp** is usually the date/time the file was last modified, not the time the file was created.
-<WRAP info>
-**NOTE:**  On un*x-ish filesystems there is no record of the file creation time
-The **ctime** field does NOT mean "creation time" as it does on FAT/NTFS filesystems, but rather, it means the "inode [C]hange time" – the time the inode itself was last modified.
-The **mtime** (last [M]odified) and atime (last [A]ccesed/read) timestamps are the same on both systems – although the precision (FAT has a granularity of two seconds, for example) and time zone may vary.
-</WRAP>
-----
-===== References =====
-https://en.wikipedia.org/wiki/Unix_file_types
-https://en.wikipedia.org/wiki/File_system_permissions#Notation_of_traditional_Unix_permissions