# Small utilities

This is a collection of small command-line utilities I have written over the years to make my daily Unix computing better.

## Contents

## 2wav

Converts media files to 16 kHz WAV for [whisper.cpp](https://github.com/ggerganov/whisper.cpp) speech recognition using [FFmpeg](!W).

[Download](small-utils/2wav).

```sh
#! /bin/sh

rate=16000

usage() {
    printf 'usage: %s [-r <rate>] src [dest]\n\nDefault rate: %d.\n' \
        "$(basename "$0")" \
        "$rate" \
        >&2 \
        ;
}

if [ "$1" = "-r" ]; then
    if [ "$#" -lt 2 ]; then
        usage
        exit 2
    fi

    rate=$2
    shift 2
fi

if [ "$#" -lt 1 ] || [ "$#" -gt 2 ]; then
    usage
    exit 2
fi

src=$1
dest=${2:-}
if [ -z "$dest" ]; then
    dest=${src%.*}.wav
fi

ffmpeg -hide_banner -i "$src" -ar "$rate" "$dest"
```

## 7z-max

A wrapper around [7-Zip](!W "7-Zip") that applies maximum compression settings.
The settings are based on a [SuperUser answer](https://superuser.com/a/1449735) by user 91735472.

[Download](small-utils/7z-max).

```sh
#! /bin/sh
set -eu

usage() {
    printf 'usage: %s [-d <MiB>] 7z-arg ...\n' "$(basename "$0")"
}

for arg in "$@"; do
    if [ "$arg" = -h ] || [ "$arg" = --help ]; then
        usage
        exit 0
    fi
done

if [ "$#" -lt 2 ]; then
    usage >&2
    exit 2
fi

d=1536m
if [ "$1" = -d ]; then
    d=${2%m}m
    shift 2
fi

7z \
    a \
    -t7z \
    -md="$d" \
    -mfb=273 \
    -mlc=0 \
    -mmc=10000 \
    -mmf=bt3 \
    -mmt \
    -mmtf \
    -mpb=0 \
    -ms \
    -mx=9 \
    -myx=9 \
    "$@" \
    ;
```

## bak

Creates backup copies of files by appending `.bak` to their names.

[Download](small-utils/bak).

```sh
#! /bin/sh
set -eu

for f in "$@"; do
    cp -ai "$f" "$f".bak
done
```

## copy and paste-clip

A pair of scripts for interacting with the X clipboard.
A little more convenient than using xclip(1) directly.
Superceded by cross-platform [pb](https://github.com/dbohdan/pb).

[Download](small-utils/copy).

```sh
#! /bin/sh
set -eu

xclip -in -sel clip "$@"
```

[Download](small-utils/paste-clip).

```sh
#! /bin/sh
set -eu

if [ $# -ne 0 ]; then
    printf 'usage: %s\n' "$(basename "$0")" >&2
    exit 2
fi

xclip -out -sel clip "$@"
```

## dl

A [curl](!W "cURL") wrapper for easy file downloads that works the same way on from NetBSD to Ubuntu.
It uses the remote filename by default.

[Download](small-utils/dl).

```sh
#! /bin/sh

dl() {
    if [ $# -lt 1 ] || [ $# -gt 2 ]; then
        printf 'usage: dl url [dest]\n' >&2
        return 1
    fi

    if [ $# -eq 2 ]; then
        curl -L -o "$2" "$1"
    else
        curl -L -O -J "$1"
    fi
}

dl "$@"
```

## exts

Lists unique file extensions in the current directory.

[Download](small-utils/exts).

```sh
#! /usr/bin/env python3

import shlex
from pathlib import Path

exts = {
    item.suffix for item in Path().iterdir()
}

print(shlex.join(sorted(exts)))
```

## mtime

Prints file modification times in the [Unix timestamp](!W) format.
When there is more than one file, prints the timestamp followed by the filename quoted for POSIX shell with [`shlex.quote`](https://docs.python.org/3/library/shlex.html#shlex.quote).
Useful for backing up and restoring modification times.


[Download](small-utils/mtime).

```sh
#! /usr/bin/env python3

import shlex
import sys
from pathlib import Path


def main() -> None:
    if len(sys.argv) == 1:
        sys.exit()

    print_paths = len(sys.argv) > 2

    for path in sys.argv[1:]:
        mtime = int(Path(path).stat().st_mtime)

        if print_paths:
            print(mtime, shlex.quote(path))
        else:
            print(mtime)


if __name__ == "__main__":
    main()
```

## t

A shortcut for the [tmux](!W "tmux") session manager that attaches to existing sessions or creates new ones.

[Download](small-utils/t).

```sh
#! /bin/sh
set -eu

if [ $# -gt 1 ]; then
    printf 'usage: %s [session]\n' "$(basename "$0")" >&2
    exit 2
fi

session=op
if [ -n "${1:-}" ]; then
    session=$1
fi

tmux a -t "$session" || tmux new -s "$session"
```

## trim

Removes trailing whitespace.

[Download](small-utils/trim).

```sh
#! /usr/bin/env python3

import fileinput
import re
import sys

regex = re.compile(r"[ \t]+$")

try:
    for line in fileinput.input(inplace=True):
        sys.stdout.write(regex.sub("", line))
except OSError as e:
    sys.stderr.write(f"{e}\n")
    sys.exit(1)
```

## ungrab

Releases grabbed keyboard/mouse input in X11.
I need it more often than I would like to in remote sessions.

[Download](small-utils/ungrab).

```sh
#! /bin/sh
xdotool key XF86Ungrab
```

## urls

Extracts URLs from text files.
The utility uses John Gruber's [URL regex patterns](https://gist.github.com/gruber/8891611).
By default, it finds both web URLs and other URI schemes.
With the `-w` option, it only finds web URLs.
The list of [TLDs](!W "TLD") in the web regular expression is outdated.

[Download](small-utils/urls).

```sh
#! /usr/bin/env python3

import argparse
import re
import shlex
import sys
from pathlib import Path
from typing import Iterator

# The URL and web URL regex patterns by John Gruber.
# https://gist.github.com/gruber/249502
RE_ALL = r"""(?i)\b((?:[a-z][\w-]+:(?:/{1,3}|[a-z0-9%])|www\d{0,3}[.]|[a-z0-9.\-]+[.][a-z]{2,4}/)(?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*\)|[^\s`!()\[\]{};:'\".,<>«»""'']))"""

# https://gist.github.com/gruber/8891611
RE_WEB = r"""(?i)\b((?:https?:(?:/{1,3}|[a-z0-9%])|[a-z0-9.\-]+[.](?:com|net|org|edu|gov|mil|aero|asia|biz|cat|coop|info|int|jobs|mobi|museum|name|post|pro|tel|travel|xxx|ac|ad|ae|af|ag|ai|al|am|an|ao|aq|ar|as|at|au|aw|ax|az|ba|bb|bd|be|bf|bg|bh|bi|bj|bm|bn|bo|br|bs|bt|bv|bw|by|bz|ca|cc|cd|cf|cg|ch|ci|ck|cl|cm|cn|co|cr|cs|cu|cv|cx|cy|cz|dd|de|dj|dk|dm|do|dz|ec|ee|eg|eh|er|es|et|eu|fi|fj|fk|fm|fo|fr|ga|gb|gd|ge|gf|gg|gh|gi|gl|gm|gn|gp|gq|gr|gs|gt|gu|gw|gy|hk|hm|hn|hr|ht|hu|id|ie|il|im|in|io|iq|ir|is|it|je|jm|jo|jp|ke|kg|kh|ki|km|kn|kp|kr|kw|ky|kz|la|lb|lc|li|lk|lr|ls|lt|lu|lv|ly|ma|mc|md|me|mg|mh|mk|ml|mm|mn|mo|mp|mq|mr|ms|mt|mu|mv|mw|mx|my|mz|na|nc|ne|nf|ng|ni|nl|no|np|nr|nu|nz|om|pa|pe|pf|pg|ph|pk|pl|pm|pn|pr|ps|pt|pw|py|qa|re|ro|rs|ru|rw|sa|sb|sc|sd|se|sg|sh|si|sj|Ja|sk|sl|sm|sn|so|sr|ss|st|su|sv|sx|sy|sz|tc|td|tf|tg|th|tj|tk|tl|tm|tn|to|tp|tr|tt|tv|tw|tz|ua|ug|uk|us|uy|uz|va|vc|ve|vg|vi|vn|vu|wf|ws|ye|yt|yu|za|zm|zw)/)(?:[^\s()<>{}\[\]]+|\([^\s()]*?\([^\s()]+\)[^\s()]*?\)|\([^\s]+?\))+(?:\([^\s()]*?\([^\s()]+\)[^\s()]*?\)|\([^\s]+?\)|[^\s`!()\[\]{};:'\".,<>?«»""''])|(?:(?<!@)[a-z0-9]+(?:[.\-][a-z0-9]+)*[.](?:com|net|org|edu|gov|mil|aero|asia|biz|cat|coop|info|int|jobs|mobi|museum|name|post|pro|tel|travel|xxx|ac|ad|ae|af|ag|ai|al|am|an|ao|aq|ar|as|at|au|aw|ax|az|ba|bb|bd|be|bf|bg|bh|bi|bj|bm|bn|bo|br|bs|bt|bv|bw|by|bz|ca|cc|cd|cf|cg|ch|ci|ck|cl|cm|cn|co|cr|cs|cu|cv|cx|cy|cz|dd|de|dj|dk|dm|do|dz|ec|ee|eg|eh|er|es|et|eu|fi|fj|fk|fm|fo|fr|ga|gb|gd|ge|gf|gg|gh|gi|gl|gm|gn|gp|gq|gr|gs|gt|gu|gw|gy|hk|hm|hn|hr|ht|hu|id|ie|il|im|in|io|iq|ir|is|it|je|jm|jo|jp|ke|kg|kh|ki|km|kn|kp|kr|kw|ky|kz|la|lb|lc|li|lk|lr|ls|lt|lu|lv|ly|ma|mc|md|me|mg|mh|mk|ml|mm|mn|mo|mp|mq|mr|ms|mt|mu|mv|mw|mx|my|mz|na|nc|ne|nf|ng|ni|nl|no|np|nr|nu|nz|om|pa|pe|pf|pg|ph|pk|pl|pm|pn|pr|ps|pt|pw|py|qa|re|ro|rs|ru|rw|sa|sb|sc|sd|se|sg|sh|si|sj|Ja|sk|sl|sm|sn|so|sr|ss|st|su|sv|sx|sy|sz|tc|td|tf|tg|th|tj|tk|tl|tm|tn|to|tp|tr|tt|tv|tw|tz|ua|ug|uk|us|uy|uz|va|vc|ve|vg|vi|vn|vu|wf|ws|ye|yt|yu|za|zm|zw)\b/?(?!@)))"""


def extract_urls(path: Path, pattern: re.Pattern) -> Iterator[str]:
    "Extract URLs from a single file using the provided regex pattern."

    with path.open("r") as f:
        content = f.read()
        yield from (match.group(0) for match in pattern.finditer(content))


def main():
    parser = argparse.ArgumentParser(description="Extract URLs from files.")

    parser.add_argument(
        "-w",
        "--web",
        action="store_true",
        help="extract web URLs only",
    )

    parser.add_argument("files", nargs="+", type=Path, help="input files to process")

    args = parser.parse_args()
    pattern = re.compile(RE_WEB if args.web else RE_ALL)

    for path in args.files:
        try:
            for url in extract_urls(path, pattern):
                print(url)
        except OSError as e:
            print(f"error processing {shlex.quote(str(path))}: {e}", file=sys.stderr)


if __name__ == "__main__":
    main()
```

## utcdate

A UTC wrapper for date(1).

[Download](small-utils/utcdate).

```sh
#! /bin/sh

TZ= date "$@"
```

## ytdl

A [yt-dlp](https://github.com/yt-dlp/yt-dlp/) wrapper optimized for highly compatible [H.264](!W) YouTube downloads.
The script handles metadata embedding, subtitle downloading, and thumbnail embedding in a single command.

[Download](small-utils/ytdl).

```sh
#! /bin/sh
# This script downloads YouTube videos for archival in a high-compatibility
# format with embedded metadata using https://github.com/yt-dlp/yt-dlp/.

set -eu

log_url=0
max_height=1080

while :; do
    case "$1" in
    -l | --log)
        log_url=1
        shift
        ;;

    -m | --max-height)
        max_height=$2
        shift 2
        ;;

    *)
        break
        ;;
    esac
done

yt-dlp \
    --add-metadata \
    --embed-chapters \
    --embed-subs \
    --embed-thumbnail \
    --format "bestvideo[vcodec*=avc1][height<=$max_height]+bestaudio[ext=m4a]" \
    --sub-langs en \
    --write-auto-subs \
    "$@" \
    ;

if [ "$log_url" -eq 1 ]; then
    for url in "$@"; do
        printf '%s\n' "$url" >> urls.txt
    done
fi
```

## See also

- [mkcd: The missing shell shortcut](/mkcd)
- [My setup](/setup)
- [now](https://wiki.tcl-lang.org/page/now): a date-time calculator for expressions like `now +21 month -5 days`
- ["Scripts I wrote that I use all the time"](https://evanhahn.com/scripts-i-wrote-that-i-use-all-the-time/), Evan Hahn (2025)

## Page metadata

URL: <https://dbohdan.com/small-utils.md>

Published 2025-01-14, updated 2025-12-03.

Tags:

- command line
- my work
- personal computing
- shell
- tools