Using the -l flag with "pg_ctl start" resolves this issue. This was a significant behavior change since PG 13.18.
David - Thank you for the quick response. Would appreciate if you have any thoughts on another logging bug (or behavior change since PG 13.18) that I documented on June 11 in #18955.
On 6/13/2025 9:46 AM, David G. Johnston wrote:
The following bug has been logged on the website:
Bug reference: 18958
Logged by: Seva Zaslavsky
Email address: szaslavsky@mpcapitallp.com
PostgreSQL version: 17.5
Operating system: Windows Server 2019
Description:
J:\Users\Public\PostgreSQL\data>"c:\Program
Files\PostgreSQL\17.5\bin\pg_ctl" start -D
"J:\Users\Public\PostgreSQL\data\5438" -o "-p 5438"
waiting for server to start....2025-06-13 08:44:06.019 EDT [10020] [] LOG:
redirecting log output to logging collector process
2025-06-13 08:44:06.019 EDT [10020] [] HINT: Future log output will appear
in directory "pg_log".
done
server started
A bit surprising I suppose, but documented.
"""
start mode launches a new server. The server is started in the background, and its standard input is attached to /dev/null (or nul on Windows). On Unix-like systems, by default, the server's standard output and standard error are sent to pg_ctl's standard output (not standard error). The standard output of pg_ctl should then be redirected to a file or piped to another process such as a log rotating program like rotatelogs; otherwise postgres will write its output to the controlling terminal (from the background) and will not leave the shell's process group. On Windows, by default the server's standard output and standard error are sent to the terminal. These default behaviors can be changed by using -l to append the server's output to a log file. Use of either -l or output redirection is recommended.
"""
Note the final sentence, neither of which was done here.
In short, while the server configuration stopped sending log data to stdout/stderr due to the log_collector directive pg_ctl has no awareness of that happening and so keeps itself attached to the process that launched it so the operator can see those streams.
David J.
