Running IBM i CL commands from an SSH/PASE shell: system, qsh, and CCSID pitfalls

Goal

Run an IBM i CL command from an SSH session into PASE (the Portable Application Solutions Environment), capture its output and exit status reliably, and avoid EBCDIC/ASCII surprises.

Prerequisites

• SSH access to the IBM i system (SSHD started, see the open-source-on-IBM-i article for autostart).
• Know whether the target CL command sends spooled output, an escape message, or plain text.

Steps

1. From a non-interactive SSH call, run a single CL command with the PASE system utility, quoting the CL command as one string:

   ssh -T user@ibmi-host 'system "DSPMSG QSYSOPR"'
   

   system is the PASE utility for invoking IBM i commands; by default spooled output the command produces and the messages it sends are written to standard output or standard error, which SSH streams back to the calling shell, and system exits non-zero when the CL command ends with an escape message.
2. For a command that needs the Qshell (QSH) environment specifically (some utilities, such as Qshell's db2, exist only there), run it non-interactively with system "QSH CMD('...')" (QSH is an alias of STRQSH) rather than opening an interactive Qshell session, which does not suit unattended callers.
3. Capture the exit status from the shell's $? after the ssh call returns; for QSH CMD(...), Qshell also sends message QSH0005 when the command's process ends normally, carrying its exit status, and QSH0006 if it ended by signal. Setting the environment variable QIBM_QSH_CMD_ESCAPE_MSG to Y turns a non-zero exit into an escape message, so system (and CL callers) see the failure; check the job log if $? alone is ambiguous.
4. Before trusting text output byte-for-byte, confirm the job's CCSID (DSPJOB OPTION(*DFNA) shows the coded character set and the default CCSID). CL jobs work in EBCDIC; PASE is ASCII-based. The system and Qshell utilities convert data on standard input/output/error, and a job CCSID of 65535 ("no conversion", the shipped QCCSID value) is a frequent cause of garbled characters. Files inside QSYS.LIB cannot be created with an ASCII CCSID through the integrated file system, so data read directly out of QSYS.LIB with a PASE tool such as cat arrives in the member's EBCDIC CCSID and needs explicit conversion.

Expected result

A single command's output and a reliable exit/return code, without opening an interactive 5250 or Qshell session per call.

Limits and test basis

Behavior described here follows the cited IBM Support pages, which are written against IBM i 7.x releases; verify exact message IDs and defaults on the target release before relying on them in an unattended pipeline. No experiment or measurement is claimed.