What does “soft/hard nofile” mean on Linux

Question

When I tried to install a software on RedHat EL5, I got the error that the expected value of soft/hard nofile is 4096 while the default is 1024. I managed to increase the number

Answer 1

As an additional aside, some distros include /etc/security/limits.d where "snippets" of limit configurations can be placed. You can create files such as this:

$ ll /etc/security/limits.d/
-rw-r--r--. 1 root root 191 Aug 18 10:26 90-nproc.conf
-rw-r--r--  1 root root  70 Sep 29 12:54 90-was-filedesc.conf

With files containing whatever limits you want to set:

$ more /etc/security/limits.d/90-nproc.conf
# Default limit for number of user's processes to prevent
# accidental fork bombs.
# See rhbz #432903 for reasoning.

*          soft    nproc     1024
root       soft    nproc     unlimited

$ more /etc/security/limits.d/90-was-filedesc.conf
root       hard    nofile    20000

I find using this method to manage these types of overrides much cleaner than mucking with /etc/security/limits.conf.

Also if you want to set both soft/hard to the same value you can use the - as the type.

$ more /etc/security/limits.d/90-was-filedesc.conf
root       -       nofile    20000