Empty PAGER variable breaks help subcommands

[graywolf-s1]

Describe the bug

When PAGER is set to empty string, help stops working.

Expected Behavior

The help would continue to work, behaving as if pager was disabled. Setting PAGER to empty string is fairly common way to disable pager usage, and works with all programs I use except awscli.

Current Behavior

list index out of range

Reproduction Steps

$ PAGER= aws s3 help

list index out of range

Possible Solution

Probably changing

if not self._exists_on_path(cmdline[0]):

to

if not (cmdline and self._exists_on_path(cmdline[0])):

should work. Assuming that is valid python, I am not pythonist.

Additional Information/Context

No response

CLI version used

aws-cli/2.17.27 Python/3.11.9 Darwin/23.6.0 source/arm64

Environment details (OS name and version, etc.)

MacOS Sodoma 14.6.1

[graywolf-s1]

diff --git a/awscli/help.py b/awscli/help.py
index 14b91c7ed..3a14c882b 100644
--- a/awscli/help.py
+++ b/awscli/help.py
@@ -136,10 +136,10 @@ class PosixHelpRenderer(PagingHelpRenderer):
 
     def _send_output_to_pager(self, output):
         cmdline = self.get_pager_cmdline()
-        if not self._exists_on_path(cmdline[0]):
+        if not (cmdline and self._exists_on_path(cmdline[0])):
             LOG.debug(
-                "Pager '%s' not found in PATH, printing raw help.", cmdline[0]
-            )
+                "Pager '%s' not found in PATH, printing raw help.",
+                cmdline[0] if cmdline else "<empty>")
             self.output_stream.write(output.decode('utf-8') + "\n")
             self.output_stream.flush()
             return

^ Seems to suffice as a fix.

[tim-finnigan]

Thanks for reaching out. This looks like a duplicate of #4972, so I'll close this and we can continue tracking there. This comment on the issue provides more background and a workaround (for when AWS_PAGER is set to an empty string):

In the pull request, it was intended that the pagers only affected command output. That being said, I'm not opposed to adding the option to control the pager functionality for the help command as well. The only thing thing I'm hesitant about is making the help pager rely on the same variables as the output pager (e.g. AWS_PAGER) as it may result in unexpected behavior for users that upgrade and not expecting the AWS_PAGER variable to affect their help output. I think if we add it, it would likely be through another environment and config variables (e.g. AWS_HELP_PAGER). This option would also give more granularity over how to page different types of outputs as well

In the meantime if you want to have the help output be printed directly to stdout, you can use a pipe (i.e. to something like cat) and the CLI will not send it to the pager.

$ aws ec2 help | cat

Please refer to the original issue for updates going forward or to add any comments.

[github-actions]

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