我使用的是 Debian 7.4 版本
那里的 /etc/pam.d/su 文件
没有启用 pam_limits.so
片段如下：
# Sets up user limits, please uncomment and read /etc/security/limits.conf
# to enable this functionality.
# (Replaces the use of /etc/limits in old login)
# session required pam_limits.so
这是为什么 ？
用谷歌搜索一下，得到的文章类似
https://my.vertica.com/docs/6.0.x/HTML/index.htm#14567.htm
On some systems the pam module called pam_limits.so is not set in the file /etc/pam.d/su. When it is not set, it prevents the conveying of limits (such as open file descriptors) to any command started with su -
In particular, the HP Vertica init script would fail to start HP Vertica because it calls the Administration Tools to start a database with the su - command. This problem was first noticed on Debian systems, but the configuration could be missing on other Linux distributions.
To resolve this issue, modify the install_vertica script and append this line to the /etc/pam.d/su file:
session required pam_limits.so
答案1
默认设置（无限制）适用于大多数人。对于大多数单一用途、单用户和小型多用户系统，限制模块不是必需的，因为您不会遇到其中任何一个；就此而言，遇到与 ulimit 相关的错误的小型系统用户可能不知道如何处理它。更重要的是，/etc/security/limits.conf没有预先配置，因为无法知道您的需求是什么，所以您仍然必须调整配置来设置限制。不妨为大多数人节省一些（少量）资源，让少数需要它的人打开该功能。