How to increase number of open files limit in Red Hat Enterprise Linux?

Solution Verified - Updated 26 Feb 2026

Environment

Red Hat Enterprise Linux 5 or later

Issue

Facing "Resource temporarily unavailable" errors while load testing a application, need to increase "nofile" and system wide limits for number of open files.

Resolution

/proc/sys/fs/file-max :- This is the number of concurrently open file descriptors allowed by the kernel. By default this number will automatically vary according to the amount of RAM in the system.

Edit/Add below kernel parameter in file /etc/sysctl.conf.
```
# vi /etc/sysctl.conf
  fs.file-max = XXXXX
```
For applying above changes run
```
# sysctl -p
```

You can verify the current value of the max-open-files limit by

# cat /proc/sys/fs/file-max
or
# sysctl -a | grep fs.file-max

Ulimit: Provides control over the resources available to the shell and processes started by the user's shell.

Each user has per-process file descriptor limits. The default is 1024. Only root can change this.
```
# ulimit -n
  1024
# su - root
# ulimit -n 16384 
# ulimit -n
  16384
```

To make the change permanent, edit the following file

For a single user

# vi /etc/security/limits.conf    
<username> soft nofile 4096
<username> hard nofile 10240

Then save the changes:
```
:wq
```

Verify the changes:

# su - username
# ulimit -Sn
  4096
# ulimit -Hn
  10240

For all users use wild card '*' instead of username

# vi /etc/security/limits.conf    
* soft nofile 4096
* hard nofile 10240

Then save the changes:
```
:wq
```

SBR

Product(s)

Red Hat Enterprise Linux

Category

Customize or extend

Tags

rhel

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