sdiff

Side-by-side file comparison and merge

TLDR

Compare files side by side

$ sdiff [file1] [file2]

Interactive merge

$ sdiff -o [output] [file1] [file2]

Set output width

$ sdiff -w [120] [file1] [file2]

Suppress common lines

$ sdiff -s [file1] [file2]

Ignore case differences

$ sdiff -i [file1] [file2]

Ignore whitespace changes

$ sdiff -b [file1] [file2]

Ignore all whitespace

$ sdiff -W [file1] [file2]

Tab-expand output

$ sdiff -t [file1] [file2]

SYNOPSIS

sdiff [-o output] [-w width] [-sbBiW] [options] file1 file2

sdiff compares two files side by side. It displays corresponding lines in parallel columns, marking differences with symbols.Output symbols indicate relationship: blank (identical), | (different), < (only in left), > (only in right). This visual format makes differences immediately apparent.Interactive merge mode (-o) creates a combined file from the two inputs. At each difference, you choose: left (l), right (r), edit left (el), edit right (er), or both (b). This enables manual resolution of differences.Width setting (-w) controls output columns. Narrow widths truncate lines; wider widths show more content. Terminal width is commonly used (e.g., -w 80 or -w $COLUMNS).Suppressing common lines (-s) shows only differences, useful for focusing on changes in files that are mostly identical.Whitespace and case options help compare files with formatting differences that aren't substantive.

PARAMETERS

-o FILE, --output FILE

Interactive merge to output file.

-w NUM, --width NUM

Output width in columns.

-s, --suppress-common-lines

Don't show identical lines.

-l, --left-column

Show only left column for common lines.

-b, --ignore-space-change

Ignore changes in whitespace amount.

-B, --ignore-blank-lines

Ignore blank line changes.

-i, --ignore-case

Case-insensitive comparison.

-W, --ignore-all-space

Ignore all whitespace.

-t, --expand-tabs

Expand tabs to spaces.

--strip-trailing-cr

Strip trailing carriage returns.

-a, --text

Treat all files as text.

-d, --minimal

Find minimal set of changes.

-H, --speed-large-files

Heuristics for large files.

INSTALL

sudo apt install diffutils

sudo dnf install diffutils

sudo pacman -S diffutils

sudo apk add diffutils

sudo zypper install diffutils

brew install diffutils

nix profile install nixpkgs#diffutils

CAVEATS

Binary files display poorly. Very long lines may be truncated. Interactive mode requires terminal. Wide files need wide terminal or scrolling. Not as feature-rich as diff for scripting.

HISTORY

sdiff is part of GNU diffutils, developed by the Free Software Foundation. Side-by-side diff originated in Unix research, providing visual comparison before graphical diff tools existed. The GNU version added interactive merge mode and various comparison options.