ov is a terminal pager.

• ov can be used instead of less, more, tail -f/-F and watch.
• ov also has an effective function for tabular text.

• 1. Feature
  • 1.1. Not supported
• 2. Install
  • 2.1. deb package
  • 2.2. rpm package
  • 2.3. MacPorts (macOS)
  • 2.4. Homebrew(macOS or Linux)
  • 2.5. winget(windows)
  • 2.6. pkg (FreeBSD)
  • 2.7. Arch Linux
  • 2.8. nix (nixOS, Linux, or macOS)
  • 2.9. Binary
  • 2.10. go install
  • 2.11. Build from source
  • 2.12. Completion
    • 2.12.1. bash
    • 2.12.2. zsh
    • 2.12.3. fish
    • 2.12.4. powershell
• 3. Usage
  • 3.1. Basic usage
    • 3.1.1. Redirect Output
  • 3.2. Config
  • 3.3. Header
    • 3.3.1. Skip
  • 3.4. Column mode
  • 3.5. Column rainbow mode
  • 3.6. Column-width
  • 3.7. Wrap/NoWrap
  • 3.8. Alternate-Rows
  • 3.9. Section
    • 3.9.1. section example
    • 3.9.2. hide other sections
  • 3.10. Multiple files
  • 3.11. Follow mode
  • 3.12. Follow name
  • 3.13. Follow all mode
  • 3.14. Follow section mode
  • 3.15. Exec mode
  • 3.16. Search
  • 3.17. Pattern
  • 3.18. Filter
  • 3.19. Caption
  • 3.20. Mark
  • 3.21. Watch
  • 3.22. Mouse support
  • 3.23. Multi color highlight
  • 3.24. Plain
  • 3.25. Converter
  • 3.26. Align
    • 3.26.1. Shrink
  • 3.27. Jump target
  • 3.28. View mode
  • 3.29. Output on exit
  • 3.30. Quit if one screen
  • 3.31. Suspend
  • 3.32. Save
• 4. How to reduce memory usage
  • 4.1. Regular file (seekable)
  • 4.2. Other files, pipes(Non-seekable)
• 5. Command option
• 6. Key bindings
• 7. Customize
  • 7.1. Style customization
  • 7.2. Customizing the bottom status line
  • 7.3. Key binding customization
• 8. VS
• 9. Work together
• 10. Contributing

• Supports files larger than memory.
• Regular files can be opened quickly even if they are large.
• Supports fixed header line display (both wrap/nowrap).
• Supports column mode, which recognizes columns by delimiter.
• Also, in column mode, there is a column-rainbow mode that colors each column.
• Support columns with fixed widths instead of delimiters.
• Supports section-by-section movement, splitting sections by delimiter.
• Dynamic wrap/nowrap switchable.
• Supports alternating row styling.
• Shortcut keys are customizable.
• The style of the effect is customizable.
• Supports follow-mode (like tail -f).
• Support follow mode by file name (like tail -F).
• Supports follow-section, which is displayed when the section is updated.
• Supports following multiple files and switching when updated(follow-all).
• Supports the execution of commands that toggle both stdout and stderr for display.
• Supports watch mode, which reads files on a regular basis.
• Support watch in exec mode (equivalent to watch command).
• Supports incremental search and regular expression search.
• Supports multi-color to highlight multiple words individually.
• Better support for Unicode and East Asian Width.
• Supports compressed files (gzip, bzip2, zstd, lz4, xz).
• Suitable for tabular text. psql, mysql, csv, etc...
• Support filter function (&pattern equivalent of less) (v0.34.0 or later).

• Does not support syntax highlighting for file types (source code, markdown, etc.)

You can download the package from releases.

curl -L -O https://github.com/noborus/ov/releases/download/vx.x.x/ov_x.x.x-1_amd64.deb
sudo dpkg -i ov_x.x.x-1_amd64.deb

You can download the package from releases.

sudo rpm -ivh https://github.com/noborus/ov/releases/download/vx.x.x/ov_x.x.x-1_amd64.rpm

sudo port install ov

brew install noborus/tap/ov

winget install -e --id noborus.ov

pkg install ov

You can install ov using an AUR helper.

Choose an AUR package:

• https://aur.archlinux.org/packages/ov (build and install from latest stable source)
• https://aur.archlinux.org/packages/ov-bin (install pre-compiled binary)
• https://aur.archlinux.org/packages/ov-git (build and install from latest git commit)

ov is available as a nix package. You can install it with

nix profile install nixpkgs#ov

if you use flakes, or using nix-env otherwise:

nix-env -iA nixpkgs.ov

You can download the binary from releases.

curl -L -O https://github.com/noborus/ov/releases/download/vx.x.x/ov_x.x.x_linux_amd64.zip
unzip ov_x.x.x_linux_amd64.zip
sudo install ov /usr/local/bin

It will be installed in $GOPATH/bin by the following command.

go install github.com/noborus/ov@latest

Or to install the latest commit from master:

go install github.com/noborus/ov@master

First of all, clone this repo with either git clone or gh repo clone, then cd to the directory, for example:

git clone https://github.com/noborus/ov.git
cd ov

Next, to install to $GOPATH/bin, run the make install command.

make install

Or, install it in a PATH location for other users to use (For example, in /usr/local/bin).

make
sudo install ov /usr/local/bin

You can generate completion scripts for bash, zsh, fish, and powershell.

ov --completion bash > /etc/bash_completion.d/ov

ov --completion zsh > /usr/share/zsh/site-functions/_ov

For zinit users.

zinit load 'https://github.com/noborus/ov/blob/master/ov.plugin.zsh'

ov --completion fish > ~/.config/fish/completions/ov.fish

ov --completion powershell completion powershell | Out-String | Invoke-Expression

(default key key) indicates the key that can be specified even after starting the same function as the command line option.

ov supports open file name or standard input.

ov filename

cat filename|ov

Used by other commands by setting the environment variable PAGER.

export PAGER=ov

See the ov site for more use cases.

Starting from v0.37.0, when redirecting the output of ov, the screen will not be displayed. To force the screen to display, use the --force-screen option.

ov --force-screen filename > output.txt

Added in v0.37.0

You can set style and key bindings in the configuration file.

ov will look for a configuration file in the following paths in descending order:

$XDG_CONFIG_HOME/ov/config.yaml
$HOME/.config/ov/config.yaml
$HOME/.ov.yaml

On Windows:

%USERPROFILE%/.config/ov/config.yaml
%USERPROFILE%/.ov.yaml

Create a config.yaml file in one of the above directories. If the file is in the user home directory, it should be named .ov.yaml.

Please refer to the sample ov.yaml configuration file.

The --header (-H) (default key H) option fixedly displays the specified number of lines.

ov --header 1 README.md

Related styling: StyleHeader.

When used with the --skip-lines (default key ctrl+s) option, it hides the number of lines specified by skip and then displays the header.

ov --skip-lines 1 --header 1 README.md

Specify the delimiter with --column-delimiter(default key is d) and set it to --column-mode(default key is c) to highlight the column.

ov --column-delimiter "," --column-mode test.csv

Regular expressions can be used for the --column-delimiter. Enclose in '/' when using regular expressions.

ps aux | ov -H1 --column-delimiter "/\s+/" --column-rainbow --column-mode

Related styling: StyleColumnHighlight,StyleColumnRainbow.

You can also color each column individually in column mode. Specify --column-rainbow(default key is ctrl+r) in addition to the --column-mode option.

Color customization is possible. Please specify 7 or more colors in config.yaml.

StyleColumnRainbow:
  - Foreground: "white"
  - Foreground: "aqua"
  - Foreground: "lightsalmon"
  - Foreground: "lime"
  - Foreground: "blue"
  - Foreground: "yellowgreen"
  - Foreground: "red"

Style specifications other than Foreground can also be specified.

StyleColumnRainbow:
    - Foreground: "white"
      Background: "red"
    - Foreground: "aqua"
      Underline: true
    - Foreground: "#ff7f00"
      Background: "blue"
      Bold: true
    - Foreground: "lime"
      Italic: true
    - Foreground: "blue"
      Dim: true
    - Foreground: "yellowgreen"
    - Foreground: "red"

Related styling: StyleColumnRainbow.

For output like ps, using --column-width is a better way to separate columns than using spaces as delimiters.

You can specify the column width with --column-width (default key alt+o).

ps aux|ov -H1 --column-width --column-rainbow

This column-width feature is implemented using guesswidth.

Supports switching between wrapping and not wrapping lines.

The option is --wrap, specify --wrap=false (default key w, W) if you do not want to wrap.

Alternate row styles with the --alternate-rows(-C) (default key C) option The style can be set with Style customization.

ov --alternate-rows test.csv

Related styling: StyleAlternate.

You can specify a section delimiter using --section-delimiter (default key alt+d).

This allows you to move between sections (default keys space and ^).

The specified line will also be treated as a section header and will remain fixed at the specified position until the next section appears at the specified position.

The start of the section can be adjusted with --section-start(default key ctrl+F3, alt+s).

The --section-delimiter is written in a regular expression (for example: "^#"). (Line breaks are not included in matching lines).

For example, if you specify "^diff" for a diff that contains multiple files, you can move the diff for each file.

The number of lines in section-header can be changed. You can specify the number of lines using the --section-header-num option or key input(default key F7).

This is an example of using the git pager.

[pager]
	diff = "ov -F --section-delimiter '^diff'"
	log = "ov -F --section-delimiter '^commit' --section-header-num 3"

Related styling: StyleSectionLine.

If you specify --hide-other-section(default key alt+-), only the current section is displayed.

ov --section-delimiter "^#" --hide-other-section README.md

This is just hidden, so it will be displayed when you move to the next section.

ov can also open multiple files.

ov file1 file2

Multiple files are each opened as a document and can be navigated using the Next Document ] key (default), Previous Document [ key (default).

Related Styling: Customizing the bottom status line.

--follow(-f)(default key ctrl+f) prints appended data and moves to the bottom line (like tail -f).

ov --follow-mode /var/log/syslog

(while :; do echo random-$RANDOM; sleep 0.1; done;)|./ov  --follow-mode

You can specify the file name to follow with --follow-name(like tail -F). Monitor file names instead of file descriptors.

ov --follow-name /var/log/nginx/access.log

--follow-all(-A)(default key ctrl+a) is the same as follow mode, it switches to the last updated file if there are multiple files.

ov --follow-all /var/log/nginx/access.log /var/log/nginx/error.log

Use the --follow-section(default key F2) option to follow by section. Follow mode is line-by-line, while follow section mode is section-by-section. Follow section mode displays the bottom section. The following example is displayed from the header (#) at the bottom.

ov --section-delimiter "^#" --follow-section README.md

Use the --exec (-e) option to run the command and display stdout/stderr separately. Arguments after (--) are interpreted as command arguments.

Shows the stderr screen as soon as an error occurs, when used with --follow-all.

ov --follow-all --exec -- make

In exec mode (other than Windows) the output is opened by opening a pty. Therefore, the command is likely to be printed in color.

ov --exec -- eza -l

Search by forward search / key(default) or the backward search ? key(default). Search can be toggled between incremental search, regular expression search, and case sensitivity. Displayed when the following are enabled in the search input prompt:

Specify true/false in config file.

CaseSensitive: false
RegexpSearch: false
Incsearch: true
SmartCaseSensitive: true

Related styling: StyleSearchHighlight

The pattern option allows you to specify a search at startup.

ov --pattern install README.md

Filter input is possible using the & key(default). The filter input creates a new document only for the lines that match the filter.

Move next document ] and previous document [ key(default) allow you to move between the filter document and the original document.

The K(shift+k) key (default) closes all documents created by the filter.

You can also specify a filter using the command line option --filter.

ov --filter "install" README.md

The filter is a regular expression.

ov --filter "^#" README.md

Also, specify the non-matching line instead of the non-matching line.

If you press ! on & while inputting a filter, non-matching lines will be targeted.

The command line option for this can be specified with --non-match-filter.

ov --non-match-filter info /var/log/syslog

If you specify both a filter option and the Quit if one screen option, the command will display the results of the filter and then quit if the results fit on one screen.

$ ps aux|ov -H1 --filter postgres --quit-if-one-screen
USER         PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
postgres    1589  0.0  0.0 221992 29952 ?        Ss   Jul24   0:02 /usr/lib/postgresql/14/bin/postgres -D /var/lib/postgresql/14/main -c config_file=/etc/postgresql/14/main/postgresql.conf
postgres    1624  0.0  0.0 222104  9544 ?        Ss   Jul24   0:00 postgres: 14/main: checkpointer 
postgres    1626  0.0  0.0 221992  8392 ?        Ss   Jul24   0:00 postgres: 14/main: background writer 
postgres    1627  0.0  0.0 221992 11464 ?        Ss   Jul24   0:00 postgres: 14/main: walwriter 
postgres    1628  0.0  0.0 222560  9928 ?        Ss   Jul24   0:01 postgres: 14/main: autovacuum launcher 
postgres    1629  0.0  0.0  76728  7112 ?        Ss   Jul24   0:01 postgres: 14/main: stats collector 
postgres    1631  0.0  0.0 222420  8904 ?        Ss   Jul24   0:00 postgres: 14/main: logical replication launcher 
noborus   193766  0.0  0.0 1603756 7552 pts/0    Rl+  10:37   0:00 ov -H1 -F --filter postgres

You can specify a caption instead of the file name in status line to display it.

ls -alF|ov --caption "ls -alF"

It can also be specified as an environment variable.

export OV_CAPTION="ls -alF"
ls -alF|ov

Mark the display position with the m key(default). The mark is decorated with StyleMarkLine and MarkStyleWidth.

Marks can be erased individually with the M key(default). It is also possible to delete all marks with the ctrl + delete key(default).

Use the >next and <previous (default) key to move to the marked position.

Related styling: StyleMarkLine.

ov has a watch mode that reads the file every N seconds and adds it to the end. When you reach EOF, add '\f' instead. Use the --watch(-T) option. Go further to the last section. The default is'section-delimiter', so the last loaded content is displayed.

for example.

ov --watch 1 /proc/meminfo

The ov makes the mouse support its control. This can be disabled with the option --disable-mouse(default key ctrl+F3, ctrl+alt+r).

If mouse support is enabled, tabs and line breaks will be interpreted correctly when copying.

Copying to the clipboard uses atotto/clipboard. For this reason, the 'xclip' or 'xsel' command is required in Linux/Unix environments.

Selecting the range with the mouse and then left-clicking will copy it to the clipboard.

Pasting in ov is done with the middle button. In other applications, it is pasted from the clipboard (often by pressing the right-click).

Also, if mouse support is enabled, horizontal scrolling is possible with shift+wheel.

This feature styles multiple words individually. .key(default) enters multi-word input mode. Enter multiple words (regular expressions) separated by spaces.

For example, error info warn debug will color errors red, info cyan, warn yellow, and debug magenta.

It can also be specified with the command line option --multi-color(-M)(default key .). For command line options, pass them separated by ,(comma).

For example:

ov --multi-color "ERROR,WARN,INFO,DEBUG,not,^.{24}" access.log

Color customization is possible. Please specify 7 or more colors in config.yaml.

StyleMultiColorHighlight:
  - Foreground: "red"
    Reverse: true
  - Foreground: "aqua"
    Underline: true
  - Foreground: "yellow"
    Background: "blue"
  - Foreground: "fuchsia"
  - Foreground: "lime"
  - Foreground: "blue"
  - Foreground: "#c0c0c0"

Related styling: StyleMultiColorHighlight.

Supports disable decoration ANSI escape sequences. The option is --plain (or -p) (default key ctrl+e).

Converter selects the engine to convert and display the text. Usually, the escape sequence is interpreted and displayed by es (default). raw displays as it is without interpreting the escape sequence.

You can specify the --converter option with [es|raw|align], and you can also specify the --raw, --align(Align) option as a shortcut option.

Added in v0.37.0

align displays the width when making Column is recognized.

Example:

c1,c2,c3
a,b,c
aaaaaaaaaaaaaaaaaaaa,bb,cc
aa,bbbbbbbbbbbbbb,cc
aa,bb,cccccccccccccccccccccc

ov --column-mode --align test.csv

Align can also shrink column.

Added in v0.37.0

Align allows columns to be shrunk and stretched by toggling with the (default key s).

To change the character displayed when columns are shrunk, set ShrinkChar in the configuration file:

ShrinkChar: '.'

Added in v0.37.0

You can specify the lines to be displayed in the search results. This function is similar to --jump-target of less. Positive numbers are displayed downwards by the number of lines from the top(1). Negative numbers are displayed up by the number of lines from the bottom(-1). . (dot) can be used to specify a percentage. .5 is the middle of the screen(.5). You can also specify a percentage, such as (50%).

This option can be specified with --jump-target(or -j) (default key j).

If section is specified as the --jump-target, the display will start from the beginning of the section as much as possible and the jump-target will be changed.

ov --section-delimiter "^#" --jump-target section README.md

Related styling: StyleJumpTarget.

You can also use a combination of modes using the --view-mode(default key p) option. In that case, you can set it in advance and specify the combined mode at once.

For example, if you write the following settings in ov.yaml, the csv mode will be set with --view-mode csv.

ov --view-mode csv test.csv

Mode:
  p:
    Header: 2
    AlternateRows: true
    ColumnMode: true
    LineNumMode: false
    WrapMode: true
    ColumnDelimiter: "|"
    ColumnRainbow: true
  m:
    Header: 3
    AlternateRows: true
    ColumnMode: true
    LineNumMode: false
    WrapMode: true
    ColumnDelimiter: "|"
  csv:
    Header: 1
    AlternateRows: true
    ColumnMode: true
    LineNumMode: false
    WrapMode: true
    ColumnDelimiter: ","
    ColumnRainbow: true

--exit-write, -X(default key Q) option prints the current screen on exit. This looks like the display remains on the console after the ov is over.

By default, it outputs the amount of the displayed screen and exits.

ov -X README.md

You can change how much is written using --exit-write-before and --exit-write-after(default key ctrl+q). --exit-write-before

--exit-write-before specifies the number of lines before the current position(top of screen). --exit-write-before 3 will output from 3 lines before.

--exit-write-after specifies the number of lines after the current position (top of screen).

--exit-write-before 3 --exit-write-after 3 outputs 6 lines.

The --quit-if-one-screen, -F option allows the program to exit immediately if the content fits within one screen. This can be useful when you only want to view small files or when you want to quickly check the content without scrolling.

If you want to enable this option by default, set QuitSmall to true in the configuration file.

QuitSmall: true

You can suspend ov with ctrl+z(default key). Normally, you can resume from suspend by typing fg.

suspended ov (use 'fg' to resume)

On Windows or if the environment variable OV_SUBSHELL is set, exit instead of fg. The process actually starts a subshell without suspending.

suspended ov (use 'exit' to resume)

Added in v0.37.0

If the file input is via a pipe, you can save it by pressing the save buffer (default S) key.

This will put you in input mode, so enter the file name. Only the buffer currently in memory is saved.

(Save)file:savefile.txt

If the file name already exists, select Overwrite, Append, or Cancel.

overwrite? (O)overwrite, (A)append, (N)cancel

Since v0.30.0 it no longer loads everything into memory. The first chunk from the beginning to the 10,000th line is loaded into memory and never freed. Therefore, files with less than 10,000 lines do not change behavior.

The --memory-limit option can be used to limit the chunks loaded into memory. Memory limits vary by file type.

Also, go may use a lot of memory until the memory is freed by GC. Also consider setting the environment variable GOMEMLIMIT.

export GOMEMLIMIT=100MiB

Normally large (10,000+ lines) files are loaded in chunks when needed. It also frees chunks that are no longer needed. If --memory-limit is not specified, it will be limited to 100.

ov --memory-limit-file 3 /var/log/syslog

Specify MemoryLimit in the configuration file.

MemoryLimitFile: 3

You can also use the --memory-limit-file option and the MemoryLimitFile setting for those who think regular files are good memory saving.

Non-seekable files and pipes cannot be read again, so they must exist in memory.

If you specify the upper limit of chunks with --memory-limit or MemoryLimit, it will read up to the upper limit first, but after that, when the displayed position advances, the old chunks will be released. Unlimited if --memory-limit is not specified.

cat /var/log/syslog | ov --memory-limit 10

It is recommended to put a limit in the config file as you may receive output larger than memory.

MemoryLimit: 1000

It can also be changed after startup.

You can customize the following items.

• StyleAlternate
• StyleHeader
• StyleOverStrike
• StyleOverLine
• StyleLineNumber
• StyleSearchHighlight
• StyleColumnHighlight
• StyleMarkLine
• StyleSectionLine
• StyleMultiColorHighlight
• StyleColumnRainbow
• StyleJumpTargetLine

Specifies the color name for the foreground and background colors. Specify bool values for Reverse, Bold, Blink, Dim, Italic, and Underline.

[Example]

StyleAlternate:
  Background: "gray"
  Bold: true
  Underline: true

Specify StyleMultiColorHighlight and StyleColumnRainbow in an array.

StyleMultiColorHighlight
  - Foreground: "red"
    Reverse: true
  - Foreground: "aqua"
    Underline: true

StyleColumnRainbow:
  - Foreground: "white"
    Background: "black"
  - Foreground: "aqua"
    Background: "black"
    Underline: true
  - Background: "lightsalmon"

You can customize the bottom status line.

[Example]

Prompt
  Normal:
    ShowFilename: false
    InvertColor: false
    ProcessOfCount: false

You can customize key bindings.

[Example]

    down:
        - "Enter"
        - "Down"
        - "ctrl+N"
    up:
        - "Up"
        - "ctrl+p"

See ov.yaml for more information.

The following software can be used instead. If you are not satisfied with ov, you should try it.

• less
  • less is versatile, feature-rich, and the de facto standard for pagers.
• most
  • most is a general-purpose pager with split-window capabilities.
• pspg
  • pspg is a pager suitable for output of psql etc.
• moar
  • moar is a pager with code highlighting.
• slit
  • slit is a pager suitable for viewing logs.
• lnav
  • lnav analyzes logs and can be used as a viewer.
• peep
  • peep is a pager that can work in a small pane.

The following are not actually pagers and do not conflict. can work together.

• bat
  • bat is an alternative to cat. It supports a lot of highlighting and automatically calls the pager.
• delta
  • delta processes the diff for easy viewing and displays it. Call the pager automatically.

Please look at the documentation portal to configure them.

We welcome contributions to this project! Here are some ways you can contribute:

1. Submit bugs and feature requests in the issue tracker.
2. Review and test open pull requests.
3. Improve or translate the documentation.
4. Write code to fix bugs or add new features.

Before contributing, please read our Code of Conduct. We expect all contributors to follow these guidelines to ensure a welcoming and friendly environment for everyone.

To start contributing:

1. Fork the repository.
2. Create a new branch for your changes.
3. Make your changes in your branch.
4. Submit a pull request with your changes.

We will review your pull request as soon as possible. Thank you for your contribution!