The meaning of ulimit-a output on AIX

AIX on ulimit-a the meaning of the output

The system resource constraints used by AIX users include two concepts---hard limits (hard limits) and soft limits (soft limits).

Hard limits has been introduced since the AIX 4.1 release. Hard limits should be set by the AIX system administrator, and only members of the security group can increase this value.
The user itself can reduce this qualification, but its changes will expire as the user exits from the system. Use the following commands to view the qualified values of the hard limits:

Ulimit-ha

Soft limits is the upper-bound value used by the AIX core to limit the use of system resources. This value can be changed by anyone, but not beyond
Hard limits value. Note here that only members of the security group can make the changes permanent, and that the normal user's change exits the system
Will fail. Use the following command to view the settings for the soft limits:

Ulimit-a

Set the stack value in/etc/security/limits to-1 Why do you see 4194304 with ulimit-a?

This problem occurs because the default stack's "Hard limit" (hard limit) is set in your operating system. To resolve this problem, you need to set the new hard limit (hard limit) for the stack in/etc/security/limits to infinity, and then set the stack limit. Such as:
Default
Fsize = 2097151
Core = 2097151
CPU =-1
data = 262144
RSS = 65536
Stack_hard =-1
stack =-1
Nofiles = 2000
Then log on with the affected user account and run the Ulimit-a command, and the new stack limit should be unlimited:
#ulimit-A
Time (seconds) Unlimited
File (blocks) Unlimited
Data (Kbytes) 131072
Stack (Kbytes) Unlimited
Memory (Kbytes) 32768
Coredump (Blocks) 2097151
Nofiles (descriptors) 2000



To view the current value specified for this shell limits, and to change them if necessary:

1.Enter the following command:

# Smit Chuser

Many problems are also caused by improper settings, which can be viewed through ulimit-a:

Pekax528:/>ulimit-a
Time (seconds) Unlimited
File (blocks) Unlimited
Data (Kbytes) Unlimited
Stack (Kbytes) 4194304
Memory (Kbytes) 32768
Coredump (Blocks) Unlimited
Nofiles (descriptors) 2000

But what does all this mean? The following paragraph read the text to understand.

Pekax528:/>more/etc/security/limits
*
* Sizes are in multiples-byte blocks, CPU time was in seconds
*
* Fsize---Soft file size in blocks
* Core---Soft core file size in blocks
* CPU---Soft per process CPU time limit in seconds
* Data---Soft data segment size in blocks
* Stack---Soft stack segment size in blocks
* RSS---Soft real memory usage in blocks
* Nofiles---Soft file descriptor limit
* Fsize_hard---Hard file size in blocks
* Core_hard---Hard core file size in blocks
* Cpu_hard---Hard per process CPU time limit in seconds
* Data_hard---Hard data segment size in blocks
* Stack_hard---Hard stack segment size in blocks
* Rss_hard---Hard real memory usage in blocks
* Nofiles_hard---Hard file descriptor limit
*
* The following table contains the default hard values if the
* Hard values are not explicitly defined:
*
* Attribute Value
*   ==========    ============
* Fsize_hard set to Fsize
* Cpu_hard set to CPU
* Core_hard-1
* Data_hard-1
* Stack_hard 8388608
* Rss_hard-1
* Nofiles_hard-1
*
* Note:a value of-1 implies "unlimited"
*

Default
Fsize = 2097151
Core = 2097151
CPU =-1
data = 262144
RSS = 65536
stack = 65536
Nofiles = 2000

Root
Fsize =-1
data =-1
stack =-1
Core =-1

Daemon

Bin

Sys

Adm:

Uucp

Guest

Nobody

Lpd

Db2inst1:
Core =-1
rss =-1
Fsize =-1
data = 491519

Oracle
Fsize =-1
data =-1
stack =-1
Core =-1
Fsize_hard =-1
Cpu_hard =-1
Data_hard =-1
Stack_hard =-1
Core_hard =-1
Core_hard =-1
rss =-1
Nofiles = 4000

Ulimit Command

Use