Commands tagged ext4 (5)

  • Before doing this, back-up all data on any ext3 partitions that are to be converted to ext4. After running previous command you MUST run fsck, is needed to return the filesystem to a consistent state. fsck -pDf /dev/yourpartition Edit /etc/fstab and change the 'type' from ext3 to ext4 for any partitions that are converted to ext4.


    5
    tune2fs -O extents,uninit_bg,dir_index /dev/yourpartition
    starchox · 2009-06-23 17:42:01 1
  • Return the creation date of a file on ext2, 3, 4 filesystems, because stat command won't show it. Useful on ubuntu, debian, and else Show Sample Output


    3
    debugfs -R "stat <$(stat --printf=%i filename)>" /dev/sdaX | grep crtime
    pggx999 · 2015-04-09 01:23:56 0
  • For slow flash memory (cheap thumb drive), ext4 is the fastest stable file system for all use cases with no relevant exception: http://www.linuxplanet.com/linuxplanet/tutorials/7208/1 Since we can usually dispense with the benefits of a journal for this type of storage, this is a way to achieve the least awful I/O-speed. Disabling the journal for an existing ext4 partition can be achieved using tune2fs -O ^has_journal /dev/sdXN Note that it is often recommended to format removable flash media with ext2, due to the lack of a journal. ext4 has many advantages over ext2 even without the journal, with much better speed as one of the consequences. So the only usecase for ext2 would be compatibility with very old software.


    2
    mke2fs -t ext4 -O ^has_journal /dev/sdXN
    michelsberg · 2013-02-15 17:24:02 0
  • XX is your device partition number like /dev/sdc1 . to see how many inodes your partition have type: df --inodes (or df -i) Default formatting with ext4 would create small inode count for the new partition if you need big count of inodes is the fstype news the correct one. in debian you can see which fstype exists as template in: vim /etc/mke2fs.conf if you format default ext for a partition size with 1TB you would get 1 Million inodes (not enough for backupStorages) but if you format with fstype news you would get hunderd of millions of inodes for the partition. you have tune /etc/sysctl.conf also with following sysconfig parameters fs.file-max = XXX fs.nr_open = XXX where XXX is the count of max inodes for whole system


    1
    mkfs.ext4 -T news /dev/sdcXX
    aysadk · 2019-07-02 13:31:23 0
  • Find out the earliest installation time of a linux system by getting the / filesystem creation time. This example is only valid the os is installed on an ext2/3/4 filesystem.


    0
    tune2fs -l $(df -P / | awk 'NR==2 {print $1}') | sed -n 's/^.*created: *//p'
    forcefsck · 2012-05-31 12:12:35 0

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scp a good script from host A which has no public access to host C, but with a hop by host B
middlehost allows ssh access from where you are but not securehost. Use nice ssh piping to simulate scp through A => B => C setting up the shell function if left as an exercise for the reader. ;-) Agent forwarding should avoid password typing.

Setting reserved blocks percentage to 1%
According to tune2fs manual, reserved blocks are designed to keep your system from failing when you run out of space. Its reserves space for privileged processes such as daemons (like syslogd, for ex.) and other root level processes; also the reserved space can prevent the filesystem from fragmenting as it fills up. By default this is 5% regardless of the size of the partition. http://www.ducea.com/2008/03/04/ext3-reserved-blocks-percentage/

check open ports without netstat or lsof

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Rename files in batch

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convert wav files to ogg
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Debug SSH at the Maximum Verbosity Level
When debugging an ssh connection either to optimize your settings ie compression, ciphers, or more commonly for debugging an issue connecting, this alias comes in real handy as it's not easy to remember the '-o LogLevel=DEBUG3' argument, which adds a boost of debugging info not available with -vvv alone. Especially useful are the FD info, and the setup negotiation to create a cleaner, faster connection.

find directory with most inodes/files
Find which directory in one filesystem that contains most inodes or files.


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