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

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 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

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 #

Cargo is the Rust package manager.

You can install cargo by

curl -sSf | sh


cargo install sd

Alpine Linux #

apk add sd

Before installing, ensure the appropriate repository is enabled.

Arch Linux #

pacman -S sd

Gentoo (unc3nsored overlay) #

emerge -av sys-apps/sd

Before installing, ensure the appropriate overlay is enabled.

Fedora #

dnf install sd

FreeBSD #

pkg install sd

Windows #

choco install sd-cli

macOS #

brew install sd

Void Linux #

xbps-install sd

Quick Guide #

  1. String-literal mode. By default, expressions are treated as regex. Use -s or --string-mode to disable regex.
> echo 'lots((([]))) of special chars' | sd -s '((([])))' ''
lots of special chars
  1. Basic regex use - let’s trim some trailing whitespace
> echo 'lorem ipsum 23   ' | sd '\s+$' ''
lorem ipsum 23
  1. Capture groups

Indexed capture groups:

> 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:

> echo "123.45" | sd '(?P<dollars>\d+)\.(?P<cents>\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:

> echo '123.45' | sd '(?P<dollars>\d+)\.(?P<cents>\d+)' '$dollars_dollars and $cents_cents'
> echo '123.45' | sd '(?P<dollars>\d+)\.(?P<cents>\d+)' '${dollars}_dollars and ${cents}_cents'
123_dollars and 45_cents
  1. Find & replace in a file
> sd 'window.fetch' 'fetch' http.js

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

To preview changes:

> sd -p 'window.fetch' 'fetch' http.js 
  1. Find & replace across project

This example uses fd.

Good ol’ unix philosophy to the rescue.

sd 'from "react"' 'from "preact"' $(fd --type file)

Same, but with backups (consider version control).

for file in $(fd --type file); do
  cp "$file" "$file.bk"
  sd 'from "react"' 'from "preact"' "$file"; 

Edge cases #

sd will interpret every argument starting with - as a (potentially unknown) flag. The common convention of using -- to signal the end of flags is respected:

$ echo "./hello foo" | sd "foo" "-w"
error: Found argument '-w' which wasn't expected, or isn't valid in this context

    sd [OPTIONS] <find> <replace-with> [files]...

For more information try --help
$ echo "./hello foo" | sd "foo" -- "-w"
./hello -w
$ echo "./hello --foo" | sd -- "--foo" "-w"
./hello -w