ulimit confusion.
Hi.
I've been playing around with ulimit and I have some questions.
If I raise a limit with $ ulimit -n 10000 is this hard or soft?
If I raise a limit with $ ulimit -n 1025 it works, then I try to lower the limit back to its default 1024 with $ ulimit -n 1024 I get an error. Why?
To edit the /etc/security.limits.conf is it safe to use vim/nano?
Thanks.
Comments
-
Hi @WarrenUK ,
If I raise a limit with $ ulimit -n 10000 is this hard or soft?
If you don't specify -H for hard or -S for soft, you are doing it for both. Look at this:
1.- Checking the hard limit:
luis@starseedstation:~$ ulimit -Hn
5242882.- Checking the soft limit:
luis@starseedstation:~$ ulimit -Sn
10243.- Modifying the limits:
luis@starseedstation:~$ ulimit -n 10254.- Checking the limits again:
luis@starseedstation:~$ ulimit -Hn
1025
luis@starseedstation:~$ ulimit -Sn
1025If I raise a limit with $ ulimit -n 1025 it works, then I try to lower the
limit back to its default 1024 with $ ulimit -n 1024 I get an error. Why?1.- What's the exact error you are getting?
2.- What user is running the command?
3.- What distro and version are you running?To edit the /etc/security.limits.conf is it safe to use vim/nano?
While you put the right information in there, there will no harm.
Regards,
Luis.0 -
@luisviveropena said:
If I raise a limit with $ ulimit -n 1025 it works, then I try to lower the
limit back to its default 1024 with $ ulimit -n 1024 I get an error. Why?1.- What's the exact error you are getting?
2.- What user is running the command?
3.- What distro and version are you running?In a fresh terminal:
$ ulimit -n 1025 works ok
$ ulimit -n 1024 works ok
$ ulimit -n 1025 error
bash: ulimit: open files: cannot modify limit: Operation not permitted0 -
Hi @WarrenUK ,
Please provide the requested information, so I can try to help you.
1.- What user is running the command? Is it a normal user, is it root?
2.- What distro and version are you running?
3.- Check /etc/security/limits.conf for limits.
Regards,
Luis.0 -
- normal user
- Kubuntu 19.10
- Nothing is set in limits.conf
Here is my output for ulimit -a
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 31181
max locked memory (kbytes, -l) 65536
max memory size (kbytes, -m) unlimited
open files (-n) 1024
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 31181
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimitedI'm confused by what is a hard and soft limit in this output?
0 -
Hi.
I've had another play around. This is confusing me.
$ ulimit -H -n
1048576
$ ulimit -S -n
1024
$ ulimit soft
$ ulimit -n 10000
$ ulimit -H -n
100000I thought the soft limit could be set up and down up to the hard limit? I can set the soft limit upwards once and then progressively lower it down and down but I can never increase it again as the hard limit comes down with the soft limit even though I am not choosing the hard limit at the terminal.
0 -
Hi @WarrenUK ,
I thought the soft limit could be set up and down up to the hard limit?
That's correct.
I can set the soft limit upwards once and then progressively lower it down
and down but I can never increase it again as the hard limit comes down
with the soft limit even though I am not choosing the hard limit at the terminal.Nop, that happens because you are lowering down the hard limit, here:
$ ulimit -n 10000
When you don't specify if it's soft or hard, the ulimit command will affect both.
Regards,
Luis.0 -
Hi Luis.
So if I do
$ ulimit soft
$ ulimit -n 10000 <<<< this will set both hard and soft limit at the same time?What is the $ ulimit soft command for then?
Many thanks.
0 -
Hi Warren,
So if I do
>
$ ulimit soft
$ ulimit -n 10000 <<<< this will set both hard and soft limit at the same time?Yes, that's right.
What is the $ ulimit soft command for then?
If you want to rise the soft limit to 10000, you do the following:
ulimit -Sn 10000
Look at this:
luis@starseedstation:~$ ulimit -Sn
1024
luis@starseedstation:~$ ulimit -Hn
524288
luis@starseedstation:~$ ulimit -Sn 10000
luis@starseedstation:~$ ulimit -Sn
10000
luis@starseedstation:~$ ulimit -Hn
524288
luis@starseedstation:~$Regards,
Luis.0
Categories
- All Categories
- 61 LFX Mentorship
- 114 LFX Mentorship: Linux Kernel
- 618 Linux Foundation IT Professional Programs
- 322 Cloud Engineer IT Professional Program
- 141 Advanced Cloud Engineer IT Professional Program
- 56 DevOps Engineer IT Professional Program
- 67 Cloud Native Developer IT Professional Program
- 6 Express Training Courses
- 6 Express Courses - Discussion Forum
- 2.3K Training Courses
- 19 LFC110 Class Forum - Discontinued
- 9 LFC131 Class Forum
- 31 LFD102 Class Forum
- 178 LFD103 Class Forum
- LFD110 Class Forum
- 24 LFD121 Class Forum
- LFD133 Class Forum
- 2 LFD137 Class Forum
- 62 LFD201 Class Forum
- 2 LFD210 Class Forum
- 1 LFD210-CN Class Forum
- 1 LFD213 Class Forum - Discontinued
- 128 LFD232 Class Forum - Discontinued
- LFD233 Class Forum
- LFD237 Class Forum
- 23 LFD254 Class Forum
- 659 LFD259 Class Forum
- 108 LFD272 Class Forum
- 1 LFD272-JP クラス フォーラム
- 4 LFD273 Class Forum
- LFS101 Class Forum
- LFS116 Class Forum
- 2 LFS145 Class Forum
- 28 LFS200 Class Forum
- 740 LFS201 Class Forum - Discontinued
- 1 LFS201-JP クラス フォーラム
- 13 LFS203 Class Forum
- 98 LFS207 Class Forum
- 301 LFS211 Class Forum
- 54 LFS216 Class Forum
- 47 LFS241 Class Forum
- 41 LFS242 Class Forum
- 38 LFS243 Class Forum
- 12 LFS244 Class Forum
- LFS245 Class Forum
- 41 LFS250 Class Forum
- 1 LFS250-JP クラス フォーラム
- LFS251 Class Forum
- 143 LFS253 Class Forum
- LFS254 Class Forum
- LFS255 Class Forum
- 1 LFS256 Class Forum
- LFS257 Class Forum
- 1.2K LFS258 Class Forum
- 10 LFS258-JP クラス フォーラム
- 108 LFS260 Class Forum
- 147 LFS261 Class Forum
- 39 LFS262 Class Forum
- 83 LFS263 Class Forum - Discontinued
- 15 LFS264 Class Forum - Discontinued
- 11 LFS266 Class Forum - Discontinued
- 21 LFS267 Class Forum
- 18 LFS268 Class Forum
- 26 LFS269 Class Forum
- 204 LFS272 Class Forum
- 1 LFS272-JP クラス フォーラム
- LFS274 Class Forum
- 3 LFS281 Class Forum
- 258 LFW211 Class Forum
- 179 LFW212 Class Forum
- 9 SKF100 Class Forum
- SKF200 Class Forum
- 908 Hardware
- 221 Drivers
- 74 I/O Devices
- 44 Monitors
- 116 Multimedia
- 210 Networking
- 102 Printers & Scanners
- 86 Storage
- 765 Linux Distributions
- 88 Debian
- 66 Fedora
- 15 Linux Mint
- 13 Mageia
- 24 openSUSE
- 144 Red Hat Enterprise
- 33 Slackware
- 13 SUSE Enterprise
- 357 Ubuntu
- 483 Linux System Administration
- 40 Cloud Computing
- 70 Command Line/Scripting
- Github systems admin projects
- 95 Linux Security
- 80 Network Management
- 108 System Management
- 52 Web Management
- 74 Mobile Computing
- 25 Android
- 34 Development
- 1.2K New to Linux
- 1.1K Getting Started with Linux
- 544 Off Topic
- 131 Introductions
- 223 Small Talk
- 22 Study Material
- 835 Programming and Development
- 284 Kernel Development
- 517 Software Development
- 975 Software
- 261 Applications
- 185 Command Line
- 3 Compiling/Installing
- 119 Games
- 318 Installation
- 65 All In Program
- 65 All In Forum
Upcoming Training
-
August 20, 2018
Kubernetes Administration (LFS458)
-
August 20, 2018
Linux System Administration (LFS301)
-
August 27, 2018
Open Source Virtualization (LFS462)
-
August 27, 2018
Linux Kernel Debugging and Security (LFD440)