The Linux Terminal Bug Freezing pgcli and How to Fix It

The cursor froze. Commands blinked unanswered. A simple pgcli query had just locked your Linux terminal in a state you couldn’t escape without killing the process.

This is the Linux Terminal bug haunting pgcli users across distributions. It appears when certain output sizes or Unicode characters hit the screen. The bug manifests differently depending on your shell, Python version, and environment variables, but the core impact is the same—your workflow halts instantly.

pgcli, the popular Postgres CLI with auto-completion and syntax highlighting, depends on Python's prompt_toolkit. When terminal state handling fails—often triggered by improper SIGINT handling or buffer overflow on wide tables—the screen can become unresponsive. The kernel reports normal process activity, but the interface does not redraw.

Common triggers for the pgcli Linux terminal bug include:

• Large result sets without proper --pager usage
• Misconfigured $TERM values (e.g., xterm-256color not supported by your terminal emulator)
• Deprecated readline overrides in .pgclirc
• Incompatibilities with newer libncurses builds

Fixes often involve forcing a safe pager:

pgcli --pager=less

Or setting $PAGER manually:

export PAGER=less

Another workaround is upgrading pgcli and prompt_toolkit to the latest releases, since patches for screen redraw are now merged upstream. Testing across bash, zsh, and fish reveals fewer failures after these upgrades.

Yet even with fixes, this bug shows how fragile CLI tools can become when library updates meet real workloads. The Linux terminal is simple, but its ecosystem carries a web of assumptions about encoding, input modes, and process handling.

If you want to debug and reproduce issues like the pgcli Linux terminal bug safely, spin up an ephemeral Postgres environment with hoop.dev. You can see the bug in action or confirm the fix—with a working database CLI—in minutes.