sd - s[earch] & d[isplace]

sd is an intuitive find & replace CLI.

The Pitch

Why use it over any existing tools?

Painless regular expressions

sd uses regex syntax that you already know from JavaScript and Python. Forget about dealing with quirks of sed or awk - get productive immediately.

String-literal mode

Non-regex find & replace. No more backslashes or remembering which characters are special and need to be escaped.

Easy to read, easy to write

Find & replace expressions are split up, which makes them easy to read and write. No more messing with unclosed and escaped slashes.

Smart, common-sense defaults

Smart-cased regular expressions also come with a sane syntax that's not opt-in. Defaults follow common sense and are tailored for typical daily use.

Comparison to sed

While sed does a whole lot more, sd focuses on doing just one thing and doing it well.

Some cherry-picked examples, where sd shines:

• Simpler syntax for replacing all occurrences:
  • sd: sd before after
  • sed: sed s/before/after/g
• Replace newlines with commas:
  • sd: sd '\n' ','
  • sed: sed ':a;N;$!ba;s/\n/,/g'
• Extracting stuff out of strings containing slashes:
  • sd: echo "sample with /path/" | sd '.*(/.*/)' '$1'
  • sed: use different delimiters every time depending on expression so that the command is not completely unreadable
  • echo "sample with /path/" | sed -E 's/.*(/.*/)/\1/g'
  • echo "sample with /path/" | sed -E 's|.*(/.*/)|\1|g'
• In place modification of files:
  • sd: sd -i before after file.txt
  • sed: you need to remember to use -e or else some platforms will consider the next argument to be a backup suffix
  • sed -i -e 's/before/after/g' file.txt

Benchmarks

Simple replacement on ~1.5 gigabytes of JSON

hyperfine -w 3 'sed -E "s/\"/\'/g" *.json >/dev/null' 'sd "\"" "\'" *.json >/dev/null' --export-markdown out.md

| Command | Mean [s] | Min…Max [s] | |:---|---:|---:| | sed -E "s/\"/'/g" *.json >/dev/null | 2.338 ± 0.008 | 2.332…2.358 | | sed "s/\"/'/g" *.json >/dev/null | 2.365 ± 0.009 | 2.351…2.378 | | sd "\"" "'" *.json >/dev/null | 0.997 ± 0.006 | 0.987…1.007 |

Result: ~2.35 times faster

Regex replacement on a ~55M json file:

hyperfine \ 'sed -E "s:(\w+):\1\1:g" dump.json >/dev/null'\ "sed 's:\(\w\+\):\1\1:g' dump.json >/dev/null"\ 'sd "(\w+)" "$1$1" dump.json >/dev/null'

| Command | Mean [s] | Min…Max [s] | |:---|---:|---:| | sed -E "s:(\w+):\1\1:g" dump.json >/dev/null | 11.315 ± 0.215 | 11.102…11.725 | | sed 's:\(\w\+\):\1\1:g' dump.json >/dev/null | 11.239 ± 0.208 | 11.057…11.762 | | sd "(\w+)" "$1$1" dump.json >/dev/null | 0.942 ± 0.004 | 0.936…0.951 |

Result: ~11.93 times faster

Installation

Cargo

sh cargo install sd

Arch Linux

sh pacman -S sd

FreeBSD

sh pkg install sd

Quick Guide

1. String-literal mode. By default, expressions are treated as regex. Use -s or --string-mode to disable regex.

```sh

echo 'lots((([]))) of special chars' | sd -s '((([])))' '' lots of special chars ```

1. Basic regex use - let's trim some trailing whitespace

```sh

echo 'lorem ipsum 23 ' | sd '\s+$' '' lorem ipsum 23 ```

1. Capture groups

Indexed capture groups:

```sh

echo 'cargo +nightly watch' | sd '(\w+)\s++(\w+)\s+(\w+)' 'cmd: $1, channel: $2, subcmd: $3' cmd: cargo, channel: nightly, subcmd: watch ```

Named capture groups:

```sh

echo "123.45" | sd '(?P\d+).(?P\d+)' '$dollars dollars and $cents cents' 123 dollars and 45 cents ```

In the unlikely case you stumble upon ambiguities, resolve them by using ${var} instead of $var. Here's an example:

```sh

echo '123.45' | sd '(?P\d+).(?P\d+)' '$dollarsdollars and $centscents' and echo '123.45' | sd '(?P\d+).(?P\d+)' '${dollars}dollars and ${cents}cents' 123dollars and 45cents ```

1. Find & replace in a file

```sh

sd -i 'window.fetch' 'fetch' http.js ```

That's it. The file is modified in-place.

To do a dry run:

```sh

sd 'window.fetch' 'fetch' http.js ```

1. Find & replace across project

This example uses fd.

Good ol' unix philosophy to the rescue.

sh sd -i 'from "react"' 'from "preact"' $(fd -t f)

Same, but with backups (consider version control).

bash for file in $(fd -t f); do cp "$file" "$file.bk" sd -i 'from "react"' 'from "preact"' "$file"; done