linux basics: startup
init: parent of all ps. PID=0
stages
linux basics: quotas
quotas
Quota specifications:
- number of inode (inode: pointer to file)
- number of block
Types:
- hard: block user when quota is reached
- soft: inform user that is about to reached the quota
install quotas
apt install quota
Enable quotas
Check config supports quota
grep QUOTA /boot/config-*
=>
CONFIG_NFT_QUOTA=m
CONFIG_NETFILTER_XT_MATCH_QUOTA=m
CONFIG_XFS_QUOTA=y
CONFIG_QUOTA=y
CONFIG_QUOTA_NETLINK_INTERFACE=y
CONFIG_PRINT_QUOTA_WARNING=y
# CONFIG_QUOTA_DEBUG is not set
CONFIG_QUOTA_TREE=m
CONFIG_QUOTACTL=y
CONFIG_QUOTACTL_COMPAT=y
Mount options
Check quota are enable in /etc/fstab at the 4th column: usrquota, grpquota option must be specified:
UUID=e248b430-aed3-4586-8a9f-2444515376e7 / ext4 errors=remount-ro,acl,usrquota,grpquota 0
Enable
quotacheck -ugm /
check quota files have been created:
ls /aquota.*
/aquota.group /aquota.user
this will fix the following error: edquota: Cannot open quotafile //aquota.user: No such file or directory No filesystems with quota detected.
turn it on:
quotaon -v /
=>
/dev/sda1 [/]: group quotas turned on
/dev/sda1 [/]: user quotas turned on
Quota commands
check quotas:
quotacheck -a
display all quotas:
repquota -a
edit quota:
** do not edit /etc/quotatab file directly but use:
edquota -u foo
edquota -g foogrp
edit grace period
grace period is the quantity of time that the system allows you to exceed the soft limit without blocking you. After that, user will be considered as he exceeded the hard limit.
edquota -t
Service
/etc/init.d/quota start
service quota start
Test it !
As root
Disk quotas for user foo (uid 1001):
Filesystem blocks soft hard inodes soft hard
/dev/sda1 16 0 0 4 5 6
Here, our foo user has: * currently consumed 4 inodes on the FS * a quota soft limit set to 5 inodes * a quota hard limit set to 6 inodes
As final user
Reach the soft limit
foo@debian:~$ touch file
foo@debian:~$ touch file 2
sda1: warning, user file quota exceeded.
Reach the hard limit
foo@debian:~$ touch file 3
sda1: write failed, user file limit reached.
touch: cannot touch '3': Disk quota exceeded
Report
root@debian:~# repquota /
=>
*** Report for user quotas on device /dev/sda1
Block grace time: 7days; Inode grace time: 7days
Block limits File limits
User used soft hard grace used soft hard grace
----------------------------------------------------------------------
root -- 3645544 0 0 113922 0 0
man -- 1496 0 0 157 0 0
lp -- 11980 0 0 1 0 0
_apt -- 12 0 0 3 0 0
systemd-timesync -- 4 0 0 2 0 0
avahi-autoipd -- 4 0 0 1 0 0
speech-dispatcher -- 4 0 0 1 0 0
colord -- 8 0 0 2 0 0
lightdm -- 32 0 0 8 0 0
ben -- 56020 0 0 1295 0 0
foo -+ 16 0 0 6 5 6 6days
Resources
- https://www.digitalocean.com/community/tutorials/how-to-set-filesystem-quotas-on-debian-10
linux basics: get command help
whereis command
search in several location /usr/bin... and returns exec file and related resources such as man, config.
whereis sl
sl: /usr/games/sl /usr/share/man/man6/sl.6.gz
which command
only search in $PATH and only return path to exec:
which sl
/usr/games/sl
type command
return how a command is interpreted:
type -a echo
echo is a shell builtin
echo is /usr/bin/echo
echo is /bin/echo