# Transforming text

_Peios / Using Peios / Peiosutils / Transforming text_

> The commands that reshape text — reordering lines, removing duplicates, substituting characters, reflowing paragraphs, and counting.

This topic covers the commands that **reshape** text: putting lines in order, dropping duplicates, swapping characters, reflowing paragraphs to a width, counting what is there. Its companion, [Viewing and joining text](/peios/using-peios/peiosutils/viewing-and-joining-text/overview.md), covers printing and combining files; this topic is about changing the text itself.

## The commands

**Ordering lines**

| Command | Purpose |
|---|---|
| [`sort`](/peios/using-peios/peiosutils/transforming-text/sort.md) | Sort lines — alphabetically, numerically, and many other ways. |
| [`shuf`](/peios/using-peios/peiosutils/transforming-text/shuf.md) | The opposite of sorting: put lines into a random order. |
| [`tsort`](/peios/using-peios/peiosutils/transforming-text/tsort.md) | Topological sort — order items so that each comes after the things it depends on. |

**Filtering lines**

| Command | Purpose |
|---|---|
| [`uniq`](/peios/using-peios/peiosutils/transforming-text/uniq.md) | Collapse or report adjacent repeated lines. |

**Substituting characters**

| Command | Purpose |
|---|---|
| [`tr`](/peios/using-peios/peiosutils/transforming-text/tr.md) | Translate, squeeze, or delete individual characters. |

**Whitespace**

| Command | Purpose |
|---|---|
| [`expand`](/peios/using-peios/peiosutils/transforming-text/expand.md) | Convert tabs into spaces. |
| [`unexpand`](/peios/using-peios/peiosutils/transforming-text/unexpand.md) | Convert runs of spaces back into tabs. |

**Reflowing and paginating**

| Command | Purpose |
|---|---|
| [`fmt`](/peios/using-peios/peiosutils/transforming-text/fmt.md) | Reflow paragraphs to a target width. |
| [`fold`](/peios/using-peios/peiosutils/transforming-text/fold.md) | Hard-wrap long lines at a fixed width. |
| [`pr`](/peios/using-peios/peiosutils/transforming-text/pr.md) | Paginate and columnate text for printing. |

**Indexing and counting**

| Command | Purpose |
|---|---|
| [`ptx`](/peios/using-peios/peiosutils/transforming-text/ptx.md) | Produce a permuted index of the words in a file. |
| [`wc`](/peios/using-peios/peiosutils/transforming-text/wc.md) | Count the lines, words, and bytes in a file. |

## Two commands that need sorted input

A theme worth knowing before you start: [`uniq`](/peios/using-peios/peiosutils/transforming-text/uniq.md) only collapses *adjacent* duplicate lines, so duplicates scattered through a file are not caught unless the file is sorted first. `sort` and `uniq` are almost always used together — and `sort -u` does both jobs in one step.

## Where to start

[`sort`](/peios/using-peios/peiosutils/transforming-text/sort.md) is the workhorse of the topic and the one with the most depth — start there.

Related content:

- [sort](/peios/using-peios/peiosutils/transforming-text/sort.md)
- [Viewing and joining text](/peios/using-peios/peiosutils/viewing-and-joining-text/overview.md)