Attempting to submit a job with ‘at’ (on my AIX system) produced the following error message:

# oslevel -s

7300-01-01-2246

# at now

shutdown -Fr

can't open job file in the /var/spool/cron/atjobs directory

The cause of the problem was the /var file system was full.

# errpt | head -2

IDENTIFIER TIMESTAMP T C RESOURCE_NAME DESCRIPTION

F7FA22C9 0414094523 I O SYSJ2 UNABLE TO ALLOCATE SPACE IN FILE SYSTEM

# errpt -aNSYSJ2

---------------------------------------------------------------------------

LABEL: J2_FS_FULL

IDENTIFIER: F7FA22C9

Date/Time: Fri Apr 14 09:45:33 EET 2023

Sequence Number: 1167

Machine Id: 00C91B804B00

Node Id: cgha2

Class: O

Type: INFO

WPAR: Global

Resource Name: SYSJ2

Description

UNABLE TO ALLOCATE SPACE IN FILE SYSTEM

Probable Causes

FILE SYSTEM FULL

Recommended Actions

INCREASE THE SIZE OF THE ASSOCIATED FILE SYSTEM

REMOVE UNNECESSARY DATA FROM FILE SYSTEM

USE FUSER UTILITY TO LOCATE UNLINKED FILES STILL REFERENCED

Detail Data

JFS2 MAJOR/MINOR DEVICE NUMBER

000A 0006

FILE SYSTEM DEVICE AND MOUNT POINT

/dev/hd9var, /var

# df -g /var

Filesystem GB blocks Free %Used Iused %Iused Mounted on

/dev/hd9var 0.94 0.00 100% 1931 83% /var

I removed some old files from /var, to free up some file system space, and then I was able to submit my 'at' job successfully.

# at now

shutdown -Fr

job root.1681429666c0.a at Fri Apr 14 09:47:46 EET 2023

Moral of the story? Monitor your file system free space, and the AIX error report for obvious problems, and fix them ASAP.