File Attributes - Revision history

Leo at 22:21, 18 August 2023

2023-08-18T22:21:35Z

@@ Line 1: / Line 1: @@
-All files in Unix like systems have file attributes. These attributes include information such as ownership (user and group owners), timestamps (file creation, modification and access times), permissions (such as the file mode, or SELinux labels).
+All files in Unix like systems have file attributes. The most common file attributes include information such as ownership (user and group owners), timestamps (file creation, modification and access times), permissions (such as the file mode, or SELinux labels).
-File attributes can be listed using the <code>stat</code> utility:
+In addition to these, there are additional filesystem-specific file attributes that enable filesystem-specific behaviors and features.
 {{highlight|lang=terminal|code=
@@ Line 14: / Line 17: @@
 Change: 2020-06-11 15:53:36.225415501 -0600
   Birth: -}}
 == Modifying Unix file attributes ==
@@ Line 66: / Line 105: @@
 # Set the system clock and then touch the file.
 # <code>debugfs -w -R 'set_inode_field /tmp/foo ctime 201001010101' /dev/sda1</code>, then <code>echo 2 > /proc/sys/vm/drop_caches</code>
 |}

Leo at 22:06, 18 August 2023

2023-08-18T22:06:40Z

← Older revision		Revision as of 22:06, 18 August 2023
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	Unix file attributes can be listed ~~with~~ the {{code\|stat}} utility.		All files in Unix like systems have file attributes. These attributes include information such as ownership (user and group owners), timestamps (file creation, modification and access times), permissions (such as the file mode, or SELinux labels).

			File attributes can be listed using the <code>stat</code> utility:

	{{highlight\|lang=terminal\|code=		{{highlight\|lang=terminal\|code=
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	Birth: -}}		Birth: -}}

			== Modifying Unix file attributes ==
	Use the following tools to modify:		Use the following tools to modify the following types of Unix attributes.
	{\| class="wikitable"		{\| class="wikitable"
	!Modify...		!Modify...
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	\|}		\|}

	==Tasks==		==Tasks and how-tos==
	===~~Preserve File Ownership/Attributes~~===		===How to copy over file ownerships and attributes===
	If you copied a set of files without preserving any of the attributes~~, rather than copying~~ the ~~data again~~, you ~~can rsync again but this time using the archive option (which enables a bunch of other flags including the one for preserving ownership, permissions, and timestamps).~~		If you copied a set of files without preserving any of the attributes but want to preserve the attributes, you have two options:

	If you're in a rut like I was after recovering data from a tape, you can do something like this:		# Run <code>rsync</code> with the <code>-a</code> archive option. Rsync should be smart enough to detect the files have identical contents and only update its file attributes without doing a full copy again.
			# Manually 'sync' the attributes using a combination of <code>touch</code>, <code>chown</code>, and <code>chmod</code> with the <code>--reference</code> option. If you're in a rut like I was after recovering data from a tape, you can do something like this:
	{{highlight\|lang=bash\|code=		{{highlight\|lang=bash\|code=
	#!/bin/bash		#!/bin/bash

Leo: file change time info

2021-12-30T05:14:20Z

file change time info

← Older revision		Revision as of 05:14, 30 December 2021
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	Use the following tools to modify:		Use the following tools to modify:
	{\| class="wikitable"		{\| class="wikitable"
	!		!Modify...
	! ~~Tool~~		!Utility
	! Example		!Example
	\|-		\|-
	! ~~Permissions~~		!Permission
	\| {{code\|chmod <permission>}}		(access modes)
			\|{{code\|chmod <permission>}}
	\|{{highlight\|lang=terminal\|code=		\|{{highlight\|lang=terminal\|code=
	# chmod 644 file.dat		# chmod 644 file.dat
	# chmod u+rw file.dat}}		# chmod u+rw file.dat}}
	\|-		\|-
	! Ownership		!Ownership
	\| {{code\|chown}} / {{code\|chgrp}}		\|{{code\|chown}} / {{code\|chgrp}}
	\|{{highlight\|lang=terminal\|code=		\|{{highlight\|lang=terminal\|code=
	## Both		## Both
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	# chgrp group file.dat}}		# chgrp group file.dat}}
	\|-		\|-
	! SELinux Context		!SELinux Context
	\| {{code\|chcon -R <context>}}		\|{{code\|chcon -R <context>}}
	\| {{highlight\|lang=terminal\|code=		\|{{highlight\|lang=terminal\|code=
	# chcon -R unconfined_u:object_r:user_home_t:s0 /home/user/.ssh/}}		# chcon -R unconfined_u:object_r:user_home_t:s0 /home/user/.ssh/}}
	\|-		\|-
	! Access Time		!File Access Time
	\| {{code\|touch -a -t YYYYMMDDhhmm.ss}}		\|{{code\|touch -a -t YYYYMMDDhhmm.ss}}
	\| {{highlight\|lang=terminal\|code=		\|{{highlight\|lang=terminal\|code=
	## Set access time to Dec 26 2020 at 1:30:30PM		## Set access time to Dec 26 2020 at 1:30:30PM
	# touch -a -t 202012261330.30 /some/file		# touch -a -t 202012261330.30 /some/file
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	# touch -a -r reference.ext target.ext}}		# touch -a -r reference.ext target.ext}}
	\|-		\|-
	! Modify Time		!File Modify Time
	\| {{code\|touch -m -t YYYYMMDDhhmm.ss}}		\|{{code\|touch -m -t YYYYMMDDhhmm.ss}}
	\| {{highlight\|lang=terminal\|code=		\|{{highlight\|lang=terminal\|code=
	## Set modification time to Dec 26 2020 at 1:30:30PM		## Set modification time to Dec 26 2020 at 1:30:30PM
	# touch -m -t 202012261330.30 /some/file		# touch -m -t 202012261330.30 /some/file
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	# touch -m -r reference.ext target.ext}}		# touch -m -r reference.ext target.ext}}
	\|-		\|-
	! Change Time		!File Change Time
	\| ~~???~~		\|N/A
	\|		\|You can't change a file's ctime. If you absolutely need to, you can [https://unix.stackexchange.com/questions/36021/how-can-i-change-change-date-of-file try these options]:

			# Set the system clock and then touch the file.
			# <code>debugfs -w -R 'set_inode_field /tmp/foo ctime 201001010101' /dev/sda1</code>, then <code>echo 2 > /proc/sys/vm/drop_caches</code>
	\|}		\|}

			==Tasks==
	== Tasks ==		===Preserve File Ownership/Attributes===
	=== Preserve File Ownership/Attributes ===
	If you copied a set of files without preserving any of the attributes, rather than copying the data again, you can rsync again but this time using the archive option (which enables a bunch of other flags including the one for preserving ownership, permissions, and timestamps).		If you copied a set of files without preserving any of the attributes, rather than copying the data again, you can rsync again but this time using the archive option (which enables a bunch of other flags including the one for preserving ownership, permissions, and timestamps).

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	}}		}}

	{{Navbox Linux}}[[Category:Linux]]		{{Navbox Linux}}
			[[Category:Linux]]

Leo: Added categories

2020-06-14T23:30:50Z

Added categories

← Older revision		Revision as of 23:30, 14 June 2020
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	done		done
	}}		}}

			{{Navbox Linux}}[[Category:Linux]]

Leo: /* Preserve File Ownership/Attributes */

2020-06-11T22:23:50Z

Preserve File Ownership/Attributes

← Older revision		Revision as of 22:23, 11 June 2020
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	# Replace files here to the root filesystem, but preserving timestamps		# Replace files here to the root filesystem, but preserving timestamps
	# Eg. ./etc/fstab gets copied to /etc/fstab, but with timestamps, permissions retained.		# Eg. ./etc/fstab gets copied to /etc/fstab, but with timestamps, permissions retained.
	find \| while read i ; do		find {{!}} while read i ; do
	if [ -f $i ] ; then		if [ -f $i ] ; then
	touch -a -m -r /$i $i		touch -a -m -r /$i $i

Leo at 22:23, 11 June 2020

2020-06-11T22:23:30Z

← Older revision		Revision as of 22:23, 11 June 2020
Line 61:		Line 61:
	\|		\|
	\|}		\|}


			== Tasks ==
			=== Preserve File Ownership/Attributes ===
			If you copied a set of files without preserving any of the attributes, rather than copying the data again, you can rsync again but this time using the archive option (which enables a bunch of other flags including the one for preserving ownership, permissions, and timestamps).

			If you're in a rut like I was after recovering data from a tape, you can do something like this:
			{{highlight\|lang=bash\|code=
			#!/bin/bash

			# Replace files here to the root filesystem, but preserving timestamps
			# Eg. ./etc/fstab gets copied to /etc/fstab, but with timestamps, permissions retained.
			find \| while read i ; do
			if [ -f $i ] ; then
			touch -a -m -r /$i $i
			chown -v --reference /$i $i
			chmod -v --reference /$i $i

			# Replace source with the local copy I have here
			rm -v /$i
			mv -v $i /$i
			fi
			done
			}}

Leo at 22:07, 11 June 2020

2020-06-11T22:07:21Z

← Older revision		Revision as of 22:07, 11 June 2020
Line 1:		Line 1:
	Unix file attributes can be listed with the {{stat}} utility.		Unix file attributes can be listed with the {{code\|stat}} utility.

	{{highlight\|lang=terminal\|code=		{{highlight\|lang=terminal\|code=

Leo: Created page with "Unix file attributes can be listed with the {{stat}} utility. {{highlight|lang=terminal|code= # stat /some/file File: ‘/some/file’ Size: 13857688196 Blocks: 27066..."

2020-06-11T22:06:58Z

Created page with "Unix file attributes can be listed with the {{stat}} utility. {{highlight|lang=terminal|code= # stat /some/file File: ‘/some/file’ Size: 13857688196 Blocks: 27066..."

New page

Unix file attributes can be listed with the {{stat}} utility.

{{highlight|lang=terminal|code=
# stat /some/file
File: ‘/some/file’
Size: 13857688196 Blocks: 27066368 IO Block: 16777216 regular file
Device: 2dh/45d Inode: 12331 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Context: unconfined_u:object_r:unlabeled_t:s0
Access: 2018-09-06 17:30:48.650399353 -0600
Modify: 2018-09-01 22:26:44.904672188 -0600
Change: 2020-06-11 15:53:36.225415501 -0600
Birth: -}}

Use the following tools to modify:
{| class="wikitable"
!
! Tool
! Example
|-
! Permissions
| {{code|chmod <permission>}}
|{{highlight|lang=terminal|code=
# chmod 644 file.dat
# chmod u+rw file.dat}}
|-
! Ownership
| {{code|chown}} / {{code|chgrp}}
|{{highlight|lang=terminal|code=
## Both
# chown user:group file.dat

## Or individually
# chown user file.dat
# chgrp group file.dat}}
|-
! SELinux Context
| {{code|chcon -R <context>}}
| {{highlight|lang=terminal|code=
# chcon -R unconfined_u:object_r:user_home_t:s0 /home/user/.ssh/}}
|-
! Access Time
| {{code|touch -a -t YYYYMMDDhhmm.ss}}
| {{highlight|lang=terminal|code=
## Set access time to Dec 26 2020 at 1:30:30PM
# touch -a -t 202012261330.30 /some/file
## Set a file based on a reference file
# touch -a -r reference.ext target.ext}}
|-
! Modify Time
| {{code|touch -m -t YYYYMMDDhhmm.ss}}
| {{highlight|lang=terminal|code=
## Set modification time to Dec 26 2020 at 1:30:30PM
# touch -m -t 202012261330.30 /some/file
## Set a file based on a reference file
# touch -m -r reference.ext target.ext}}
|-
! Change Time
| ???
|
|}