Written 30 Aug 2026. This is a how-to, not a product card.

Change characters

After SSH works, change characters with tr so a mixed line is easier to clean. You don't need a file manager for this.

Pull one column pulled fruit apart from color. Tonight you change characters: tr. Tr swaps or deletes characters. Start with a tiny fruit list. You are still only looking. The computer does not need a file manager for this one job.

Skip until SSH already works

SSH from the couch should already get you a prompt. If one column pulled is what you want, that is pull one column. If columns side by side are what you want, that is join columns side by side. If copies dropped are what you want, that is drop duplicate lines.

What this is

tr changes characters. You send text in, tr prints the changed text out. It does not rewrite a file unless you redirect. Start with commas to newlines, or upper case to lower case. It is not cut. Cut pulls a column. It is not paste. Paste joins columns from two files.

Practice tr in home

SSH into the computer. Make a tiny practice file:

printf 'apple,red\nbanana,yellow\npear,green\n' > ~/fruit.csv

cat ~/fruit.csv

Turn commas into newlines:

tr ',' '\n' < ~/fruit.csv

You want each word on its own line. That is enough for tonight. Practice only in home.

Debian and Ubuntu usually already have tr. Don't make apt the job. If tr is missing:

sudo apt install coreutils

Then stop. That install is not the lesson.

When you are done, throw the practice files away. Careful delete only. That is delete a file carefully. Skip rm -rf.

rm ~/fruit.csv

Useful extras, still looking only

Optional: from a typed line, no file:

printf 'apple,red,banana\n' | tr ',' '\n'

Optional: lower case:

printf 'Apple,RED\n' | tr 'A-Z' 'a-z'

Optional: delete commas:

tr -d ',' < ~/fruit.csv

Optional: squeeze extra spaces:

printf 'apple red\n' | tr -s ' '

Optional: cut then tr:

cut -d, -f1 ~/fruit.csv | tr 'A-Z' 'a-z'

Don't make those required. You can stay on commas to newlines.

What this is not

This is not cut. That is pull one column. It is not paste. That is join columns side by side. It is not uniq. That is drop duplicate lines. It is not sort. That is put lines in order. It is not grep. That is find a word in a file. It is not opening SSH to the internet. That is keep the computer on the house network.

What next

Need one column? Pull one column. Need columns side by side? Join columns side by side. Need copies dropped? Drop duplicate lines. Keep SSH on the house network: keep the computer on the house network. Don't forward port 22.

Skip

• Skip if SSH still fails. Finish SSH from the couch first.
• Skip cut, paste, uniq, and sort as tonight's job. Those pages already exist.
• Skip tr into rm. Tr prints. Don't mix delete into this drill.
• Skip files under /etc, SSH folders, or paths you don't own. Practice only in home.
• Skip rm -rf. Careful delete only: delete a file carefully.
• Skip opening SSH to the internet so you can do this from a coffee shop. That is keep the computer on the house network. Don't forward port 22.