Struct Args 

pub struct Args {

    pub blocks: bool,
    pub chop: bool,
    pub squeeze_blanks: bool,
    pub header: Option<String>,
    pub rscroll: String,
    pub window: Option<u16>,
    pub word_wrap: bool,
    pub follow_name: bool,
    pub exit_follow_on_close: bool,
    pub content_type: Option<String>,
    pub dim: bool,
    pub display: Option<String>,
    pub examples: bool,
    pub filter: Vec<String>,
    pub follow: bool,
    pub follow_suspend_on_motion: bool,
    pub format: Option<String>,
    pub grep: Vec<String>,
    pub ignore_case: bool,
    pub IGNORE_CASE: bool,
    pub no_hilite_search: bool,
    pub no_init: bool,
    pub quit_if_one_screen: bool,
    pub quit_on_intr: bool,
    pub quit_at_eof: bool,
    pub QUIT_AT_EOF: bool,
    pub head: Option<usize>,
    pub hex: bool,
    pub hex_group: usize,
    pub image_width: Option<usize>,
    pub line_numbers: bool,
    pub list_formats: bool,
    pub live: bool,
    pub manual: bool,
    pub mouse: bool,
    pub no_color: bool,
    pub no_image: bool,
    pub no_preprocess: bool,
    pub output: Option<String>,
    pub preprocess: Option<String>,
    pub prettify: bool,
    pub prompt: Option<String>,
    pub raw_control_chars: bool,
    pub truecolor: String,
    pub status_style: String,
    pub prompt_style: String,
    pub record_start: Option<String>,
    pub stdout: bool,
    pub tab_width: u8,
    pub tag: Option<String>,
    pub tag_file: Option<PathBuf>,
    pub tail: Option<usize>,
    pub files: Vec<PathBuf>,
}

Fields

blocks: bool

Render images with Unicode half-blocks (▀, fg=top pixel, bg=bottom pixel) for ~2× vertical detail instead of the default character ramp.

chop: bool

Chop long lines instead of wrapping.

squeeze_blanks: bool

Collapse runs of two or more consecutive blank lines into a single blank line at display time. Real line numbers, search, and tag jumps are unaffected (they reference the original count). Mirrors less -s.

header: Option<String>

Pin the top L source lines (and the left C columns, when horizontal scroll is supported) at the top of the viewport. Form: L or L,C. Default 0,0 (off). Mirrors less --header. Runtime adjustment: :header L [C].

rscroll: String

Character to show at the right edge of a chopped line (-S chop mode) indicating “more content right”. Default >. Pass an empty string to disable. Mirrors less --rscroll=c.

window: Option<u16>

PageDown / PageUp step size in lines. Default: full screen height (body rows). Half-page commands always advance by half the screen regardless. Mirrors less -zn / --window=n.

word_wrap: bool

In wrap mode, break lines on whitespace boundaries instead of mid-character when possible. Falls back to mid-character break when no whitespace fits in the row. Mirrors less --wordwrap.

follow_name: bool

Follow the file by path rather than by descriptor (matches tail -F / less --follow-name). tess already does this — rotation and truncation are detected on every poll and the source re-opens by path (since 0.25.0). This flag is accepted for compatibility and currently has no behavioral effect.

exit_follow_on_close: bool

In follow mode with piped stdin, exit when the upstream writer closes the pipe. Default behavior (off): tess remains open on the captured content after stdin EOF. Mirrors less --exit-follow-on-close.

content_type: Option<String>

Force the content type for --prettify (otherwise auto-detected from the filename extension and the first bytes). Values: auto, raw, json, yaml, toml, xml, html, csv. Setting this implies --prettify (unless the value is raw/auto).

dim: bool

With --filter, dim non-matching lines instead of hiding them. Keeps surrounding context visible.

display: Option<String>

Render each parsed line through this template instead of showing the raw line. Syntax: <fieldname> placeholders, \< for literal <, \\ for literal \. Example: --display '[<time>] <status> <msg>'. Overrides the format’s display key (if set). Requires --format. Search still matches against the raw line.

examples: bool

Print a curated list of usage examples and exit.

filter: Vec<String>

Filter visible lines by parsed field. Repeatable; multiple filters AND. Operators: = (exact), != (exact ≠), ~ (regex), !~ (regex ≠), <, <=, >, >= (numeric if both sides parse as numbers, else lexicographic). Examples: --filter status=500, --filter ip~^10\., --filter 'status>=500' (quote < and > to avoid shell redirection). Requires --format.

follow: bool

Follow mode: keep watching the source for new bytes (like tail -f). Jumps to the bottom on startup. Toggle with Shift-F at runtime.

follow_suspend_on_motion: bool

In follow mode, any user motion (scroll, page, goto-line) suspends following. Re-engage with Shift-F. Default off: today’s behavior (movement keeps follow on; auto-scroll suspended while the viewport is not at bottom). Matches less +F semantics when enabled.

format: Option<String>

Apply a named log format (built-in or user-defined in ~/.config/tess/formats.toml). Required by --filter.

grep: Vec<String>

Filter visible lines by regex against the raw line. Repeatable; multiple --grep arguments AND. Works on any input — no --format required. Composes with --filter (both must match) and with --dim (non-matches stay visible but faded). Example: --grep error --grep '^\['.

ignore_case: bool

Smart-case search. /, ?, --grep, and --filter’s ~ / !~ operators match case-insensitively unless the pattern contains an uppercase character. Mirrors less -i / ripgrep / vim smartcase. Mutually exclusive with -I. Runtime toggle: :case.

IGNORE_CASE: bool

Force case-insensitive search regardless of pattern case. Mirrors less -I. Mutually exclusive with -i.

no_hilite_search: bool

Disable search-match highlighting by default. Search still navigates (n / N jump to matches); the visual reverse-video highlight is suppressed. Runtime toggle: :hlsearch / :nohlsearch. Mirrors less -G.

no_init: bool

Don’t enter the alt-screen on startup. Content remains in terminal scrollback after exit. Crucial for piped use and debugging. Mirrors less -X / --no-init.

quit_if_one_screen: bool

Exit immediately (without paging) if the entire source fits on one screen. Ignored with piped stdin in follow mode. Mirrors less -F.

quit_on_intr: bool

Accepted for less compatibility. tess always exits on Ctrl-C (Ctrl-C → Command::Quit in the input table), so this flag is a no-op. Provided so existing less invocations work unchanged.

quit_at_eof: bool

Quit when the user tries to scroll forward past end-of-file for the second time. Mirrors less -e. Mutually exclusive with -E.

QUIT_AT_EOF: bool

Quit the first time end-of-file is reached. Mirrors less -E.

head: Option<usize>

Show only the first N lines of the source. Mutually exclusive with –tail.

hex: bool

Render the source as an xxd-style hex dump instead of byte-faithful text. 16 bytes per row, offset prefix, ASCII gutter. Mutually exclusive with parsing- and rendering-oriented flags.

hex_group: usize

Hex characters per group in --hex mode. One of 2, 4, 8, 16, 32 (default 4, matching xxd). 32 means the whole row as a single group with no spacing between hex pairs. Requires --hex. Can be changed at runtime with :hex N.

image_width: Option<usize>

Target width in columns for image rendering. Defaults to the terminal width interactively, or 80 when exporting to a file/stdout.

line_numbers: bool

Show line numbers.

list_formats: bool

Print available log formats and their named fields, then exit.

live: bool

Live mode: re-read the file when its on-disk content changes (mtime, size, or inode). Use this for files rewritten in place — source files being edited, files saved by an editor or AI agent. Different from --follow (which watches for appended bytes); the two are mutually exclusive. Press R inside the pager to force a reload.

manual: bool

Print the full user manual and exit.

mouse: bool

Enable mouse capture: click rows in the file picker / help overlay, and scrollwheel scrolls the body. Trade-off: most terminals disable their native text selection while mouse capture is on.

no_color: bool

Show raw control bytes as ^X glyphs (pre-0.18 default). Disables SGR / OSC interpretation. Honoured also by the NO_COLOR environment variable (any non-empty value) and CLICOLOR=0.

no_image: bool

Treat a detected image file as raw/normal text instead of rendering it as ASCII art. Has no effect on non-image inputs.

no_preprocess: bool

Ignore $LESSOPEN. Useful when LESSOPEN is exported but not wanted for one invocation.

output: Option<String>

Non-interactive batch mode: apply –filter / –grep / –head / –tail / –prettify to the source and write the resulting raw bytes to FILE, then exit. Use - for stdout (--stdout is a synonym). Skips the alt-screen and raw mode entirely. With --follow, doesn’t exit — keeps appending matching new bytes to FILE as they arrive (Ctrl-C to stop). Not compatible with --live.

preprocess: Option<String>

Pipe the source file through this command before rendering. Must start with |; %s is substituted with the file path. Example: --preprocess '|pdftotext %s -'. Overrides $LESSOPEN.

prettify: bool

Pretty-print structured content (JSON, YAML, TOML, XML, HTML, CSV). Detects the type from the filename extension or the first bytes; use --content-type=NAME to override. Static files only — not allowed with --follow, --live, or --filter. Toggle interactively with Shift-P; force a type with -P then a letter (j/y/t/x/h/c).

prompt: Option<String>

Replace the hardcoded status format with a templated string. Uses the same <field> syntax as --display. Available fields: label, top, bottom, total, pct, rec-top, rec-bottom, rec-total, rec-block, wrap-offset, format-tag, filter-tag, grep-tag, hide-tag, search-tag, pretty-tag, live-tag, follow-tag. Per-format default can be set via prompt = '...' in formats.toml. Mutually exclusive with –hex.

raw_control_chars: bool

Pass every byte to the terminal raw, including cursor moves and non-SGR escape sequences. Risky: scroll math may break on long lines. Less-style -r. Mutually exclusive with –no-color.

truecolor: String

Truecolor (24-bit RGB) handling. auto (default) checks $COLORTERM and downsamples when truecolor isn’t advertised; never always downsamples to the 256-color palette; always passes RGB through regardless of terminal capability.

status_style: String

Style for the status row. Comma-separated tokens: bold, dim, italic, underline, reverse, fg=COLOR, bg=COLOR. COLOR is a named color (black..white, optional bright- prefix), #RRGGBB, or an indexed value (0–255). Empty string disables theming. Default: reverse.

prompt_style: String

Style for --prompt output (and per-format prompt_style). Same grammar as --status-style. Default: empty (no extra styling on top of what the prompt template itself emits).

record_start: Option<String>

Treat lines matching REGEX as record boundaries. Lines that don’t match are joined to the preceding record. Affects search, filter, grep, and the status line — all operate on whole records when set. Overrides the active –format’s record_start if both are present. Without –format, this is the only way to enable records mode for plain text. Example: –record-start ‘^[’

stdout: bool

Synonym for --output -: write the batch-mode output to stdout.

tab_width: u8

Tab stop width (default 8).

tag: Option<String>

Jump to the tag NAME at startup (requires a tags file).

tag_file: Option<PathBuf>

Path to the tags file. Default: walk up from CWD looking for tags.

tail: Option<usize>

Show only the last N lines of the source. For files this skips most of the index work — useful for huge logs. Combine with -f for tail -f. Mutually exclusive with –head. Streaming stdin is not supported.

files: Vec<PathBuf>

Files to view (only the first is opened in MVP).

Trait Implementations

impl Args for Args

fn group_id() -> Option<Id>

Report the ArgGroup::id for this set of arguments

fn augment_args<'b>(__clap_app: Command) -> Command

Append to Command so it can instantiate Self via FromArgMatches::from_arg_matches_mut

fn augment_args_for_update<'b>(__clap_app: Command) -> Command

Append to Command so it can instantiate self via FromArgMatches::update_from_arg_matches_mut

impl Clone for Args

fn clone(&self) -> Args

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl CommandFactory for Args

fn command<'b>() -> Command

Build a Command that can instantiate Self.

fn command_for_update<'b>() -> Command

Build a Command that can update self.

impl Debug for Args

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl FromArgMatches for Args

fn from_arg_matches(__clap_arg_matches: &ArgMatches) -> Result<Self, Error>

Instantiate Self from ArgMatches, parsing the arguments as needed.

fn from_arg_matches_mut( __clap_arg_matches: &mut ArgMatches, ) -> Result<Self, Error>

Instantiate Self from ArgMatches, parsing the arguments as needed.

fn update_from_arg_matches( &mut self, __clap_arg_matches: &ArgMatches, ) -> Result<(), Error>

Assign values from ArgMatches to self.

fn update_from_arg_matches_mut( &mut self, __clap_arg_matches: &mut ArgMatches, ) -> Result<(), Error>

Assign values from ArgMatches to self.

impl Parser for Args

fn parse() -> Self

Parse from std::env::args_os(), exit on error.

fn try_parse() -> Result<Self, Error>

Parse from std::env::args_os(), return Err on error.

fn parse_from<I, T>(itr: I) -> Self

where I: IntoIterator<Item = T>, T: Into<OsString> + Clone,

Parse from iterator, exit on error.

fn try_parse_from<I, T>(itr: I) -> Result<Self, Error>

where I: IntoIterator<Item = T>, T: Into<OsString> + Clone,

Parse from iterator, return Err on error.

fn update_from<I, T>(&mut self, itr: I)

where I: IntoIterator<Item = T>, T: Into<OsString> + Clone,

Update from iterator, exit on error.

fn try_update_from<I, T>(&mut self, itr: I) -> Result<(), Error>

where I: IntoIterator<Item = T>, T: Into<OsString> + Clone,

Update from iterator, return Err on error.