process_output(9)

💅 process_output — the output post processor, bestie

okay so real talk, this one's from the Kernel API Manual (yeah, the process_output(9) girlies know) and she is literally the post-processing queen of tty output. buckle up 🎀

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🌸 SYNOPSIS 🌸

int process_output (u8 c , struct tty_struct *tty );

✨ ARGUMENTS ✨

• c — the character, or like... a partial unicode symbol 👀 (yes, partial. she's doing her best)
• tty — the terminal device in question, the whole vibe holder

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🦋 DESCRIPTION 🦋

So what she does is: output one character with OPOST processing. That's it. That's the whole gig. One char, fully post-processed, slay ✨

Locking tea 🔒: you're gonna want output_lock to protect the column state and the space left. Also (and this is the part where it gets spicy) — this function is called from n_tty_write under the tty layer write lock. So like, the lock situation is already handled upstream, no cap.

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💖 RETURN 💖

Returns -1 when the output device is full and the character has to be retried 😭 like when your fave is too busy to text back. the char will get another chance tho 🫶

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👑 SEE ALSO 👑

Kernel file ./drivers/tty/n_tty.c — and honestly the whole friend group:

• n_tty_kick_worker(9)
• n_tty_write_wakeup(9)
• put_tty_queue(9)
• reset_buffer_flags(9)
• n_tty_flush_buffer(9)
• is_utf8_continuation(9)
• is_continuation(9)
• do_output_char(9)
• process_output_block(9)
• __process_echoes(9)
• add_echo_byte(9)
• echo_move_back_col(9)
• echo_set_canon_col(9)
• echo_erase_tab(9)
• echo_char_raw(9)
• echo_char(9)
• finish_erasing(9)
• eraser(9)
• isig(9)
• n_tty_receive_break(9)
• n_tty_receive_overrun(9)
• n_tty_receive_parity_error(9)
• n_tty_receive_char_flow_ctrl(9)
• n_tty_receive_char(9)
• n_tty_receive_buf_common(9)
• n_tty_set_termios(9)
• n_tty_close(9)
• n_tty_open(9)
• copy_from_read_buf(9)
• canon_copy_from_read_buf(9)
• job_control(9)
• n_tty_read(9)
• n_tty_write(9)
• n_tty_poll(9)
• n_tty_inherit_ops(9)

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mwah 💜 that's the whole page, go read the source bestie it's giving main character energy

— from ./drivers/tty, dated October 2026, in the process_output(9) era 🎀✨