# Columns and Characters: cut and tr

cut keeps the columns you name with -f, splitting each line at the delimiter you give with -d (or keeps character positions with -c), and tr changes characters one for one, such as capitals into lowercase, or deletes them with -d.

Apprentice · Unix · Linux · Updated November 10, 2026

## After this lesson you can

- Take columns out of a CSV file with cut -d and -f, or characters with cut -c
- Change characters with tr, such as capitals into lowercase, or delete them with tr -d

## Key takeaways

- cut -d, -f4 splits each line at its commas and keeps the fourth column. -f3,5 keeps two columns, and -f2-4 keeps the second to the fourth.
- Without -d, cut splits at tabs, so the lines of a CSV come out whole. Always give the delimiter.
- cut -c1-7 keeps the first seven characters of each line, such as the year and month of a date.
- tr 'A-Z' 'a-z' changes each capital into its lowercase letter, and tr -d deletes the characters you list. tr reads only from a pipe or <.

Bea wants to email her customers about the holiday menu. Every email address is in `orders.csv`, but buried among dates, cakes and totals, and each regular customer is in there dozens of times. Copying the addresses out by hand would take an evening, and a spreadsheet can delete columns but won't fix the capital letters some customers typed. Two small commands do it in a line: `cut` takes a column out of every line, and `tr` fixes characters. You'll reach for them whenever you need one column from a sign-up sheet, a report or a log.

The examples use the bakery folder from *Pipes: |* (its setup lines make it). Go into it with `cd ~/terminal-practice/bakery`.

## cut: one column

`cut` keeps the columns you ask for. Tell it two things: what separates one column from the next, with `-d` (for *delimiter*, the character between columns, here a comma), and which column you want, with `-f` (for *field*, cut's word for a column), counting from 1. Read `-d,` aloud as "delimiter comma". The email is the fourth column:

```bash
cut -d, -f4 orders.csv | head -n 4
```

```text
email
zoe.hart@example.com
luis.ortega@example.com
Rosa.Silva@example.com
```

List several fields with commas between them, or a range with a dash: `-f2-4` keeps the second to the fourth.

```bash
cut -d, -f3,5 orders.csv | head -n 4
```

```text
customer,city
Zoe Hart,Portland
Luis Ortega,Bend
Rosa Silva,Corvallis
```

The header line comes along, because it's a line like any other; add `tail -n +2` when you don't want it.

## Forget -d, and nothing is cut

Leave out `-d,` and `cut` splits at tabs, its default. A CSV file has no tabs, so every line is one long column, and `cut` prints it whole:

```bash
cut -f4 orders.csv | head -n 2
```

```text
order,date,customer,email,city,item,qty,total
1001,2025-01-01,Zoe Hart,zoe.hart@example.com,Portland,sourdough loaf,3,24.00
```

There's no error, only lines that didn't change. One more limit: `cut` doesn't understand quotes, so a field with a comma inside it, such as `"Lopez, Maya"`, splits in the wrong place. Bea's export has none.

## cut -c: by character

`-c` (for *characters*) counts character positions instead of fields. A date such as `2025-03-14` starts with its year and month, the first seven characters, so this counts the orders in each month with the pattern from *Count, Sort, Remove Duplicates: wc, sort and uniq*:

```bash
cut -d, -f2 orders.csv | tail -n +2 | cut -c1-7 | sort | uniq -c | head -n 3
```

```text
     45 2025-01
     40 2025-02
     44 2025-03
```

## tr: change characters

Back to the mailing list. `sort -u` keeps each address once, and `wc -l` counts them:

```bash
cut -d, -f4 orders.csv | tail -n +2 | sort -u | wc -l
```

```text
40
```

Forty addresses, but Bea has only 20 customers. Some customers typed their address with capitals now and then:

```bash
grep -i "rosa.silva" orders.csv | cut -d, -f4 | head -n 3
```

```text
Rosa.Silva@example.com
rosa.silva@example.com
rosa.silva@example.com
```

Email ignores capitals, but `sort` doesn't, so Rosa counts twice. `tr` (*translate*) swaps characters one for one: each character in the first set becomes the character in the same place in the second. `'A-Z'` (read "A to Z") is every capital, and `'a-z'` every lowercase letter:

```bash
echo "Rosa.Silva@example.com" | tr 'A-Z' 'a-z'
```

```text
rosa.silva@example.com
```

Put `tr` in the pipeline before `sort -u`, and save the list:

```bash
cut -d, -f4 orders.csv | tail -n +2 | tr 'A-Z' 'a-z' | sort -u > mailing-list.txt
wc -l mailing-list.txt
head -n 3 mailing-list.txt
```

```text
20 mailing-list.txt
aiko.tanaka@example.com
ben.carter@example.com
caleb.wells@example.com
```

Twenty customers, twenty addresses. The same trick turns a CSV into tab-separated columns: `tr ',' '\t'`.

## tr -d deletes, and tr reads only its input

Some exports put quotes around every field, and `cut` keeps them. `tr -d` (for *delete*) removes every character you list. Careful: `-d` means *delimiter* to `cut` and *delete* to `tr`. Each command chooses what its letters mean.

```bash
echo '"Zoe Hart","Portland","sourdough loaf"' | tr -d '"'
```

```text
Zoe Hart,Portland,sourdough loaf
```

The slip people make with `tr` is giving it a file name. It never takes one: it reads only standard input.

```bash
tr 'A-Z' 'a-z' orders.csv
```

```text
tr: extra operand 'orders.csv'
Try 'tr --help' for more information.
```

Send the file in through a pipe, or with `<` from *Three Streams: Output, Errors and Input*:

```bash
tr 'A-Z' 'a-z' < orders.csv | head -n 2
```

```text
order,date,customer,email,city,item,qty,total
1001,2025-01-01,zoe hart,zoe.hart@example.com,portland,sourdough loaf,3,24.00
```

## Check yourself

2 questions to try on the lesson page.

## So what

With `cut` and `tr`, any column of any export is yours to count, clean and save: an email list, the months that sell best, the cities to deliver to.

## Key terms

- [cut](https://www.ask-codey.com/glossary/cut)
- [tr](https://www.ask-codey.com/glossary/tr-unix)
- [Delimiter](https://www.ask-codey.com/glossary/delimiter)
- [CSV File](https://www.ask-codey.com/glossary/csv-file)

## Cheat sheets

- [Columns and Characters: cut and tr](https://www.ask-codey.com/cheat-sheets/bash-cut-and-tr-cheat-sheet)

## Related

- [Count, Sort, Remove Duplicates: wc, sort and uniq](https://www.ask-codey.com/lessons/bash-count-sort-unique)
- [Tee and Xargs: Splitting and Feeding](https://www.ask-codey.com/lessons/bash-tee-and-xargs)

Source: https://www.ask-codey.com/lessons/bash-cut-and-tr