Written 1 Sep 2026. This is a how-to, not a product card. Buy links are not tagged yet.

See whether two leftover-box files match byte for byte

After leftover-box comm, compare leftover-box files byte for byte with leftover-box cmp so leftover-box practice copies (and leftover-box echo drills) show whether two leftover-box files match exactly. You do not need extra leftover-box system software for this.

Compare leftover-box sorted leftover-box lists asked leftover-box sorted leftover-box lists to leftover-box compare with comm ~/comm-a.txt ~/comm-b.txt. Tonight is leftover-box match leftover-box files byte for byte: leftover-box cmp. Cmp means compare leftover-box files byte for byte. Night one prefers two tiny leftover-box practice files, then cmp ~/cmp-a.txt ~/cmp-b.txt so leftover-box silence means leftover-box match, and a leftover-box short leftover-box message means leftover-box first leftover-box difference, safe peek. When leftover-box files match, leftover-box cmp prints nothing and leftover-box gives the prompt back. When leftover-box files differ, leftover-box cmp names leftover-box where leftover-box first leftover-box byte leftover-box differs. That is not leftover-box diff. Diff compares leftover-box files for leftover-box line leftover-box edits. That is see whether two leftover-box files are the same. Skip leftover-box diff as tonight's job — leftover-box diff exists. That is not leftover-box comm. Comm compares leftover-box sorted leftover-box lists. That is compare leftover-box sorted leftover-box lists. Skip leftover-box comm as tonight's job — leftover-box comm exists. That is not leftover-box sha256sum. Sha256sum fingerprints leftover-box one leftover-box file. That is check a leftover-box file fingerprint. Skip leftover-box sha256sum as tonight's job — leftover-box sha256sum exists. That is not leftover-box join. Join matches leftover-box files on a shared leftover-box field. That is match leftover-box files on a shared leftover-box field. Skip leftover-box join as tonight's job — leftover-box join exists. That is not leftover-box paste. That is join leftover-box columns side by side. Skip leftover-box paste as tonight's job — leftover-box paste exists. That is not leftover-box diff as the leftover-box lesson again — leftover-box diff exists. Night one is leftover-box cmp on two tiny leftover-box home files. That is not leftover-box awk, leftover-box SQL, or a leftover-box spreadsheet app. You are still only practicing in home. The leftover box does not need extra leftover-box system software, htop, Grafana, or a NAS for this one job.

Skip until SSH already works

SSH from the couch should already get you a prompt. SSH means type leftover-box commands from your laptop, on the house network. If leftover-box comm is what you want (compare leftover-box sorted leftover-box lists), that is compare leftover-box sorted leftover-box lists. Skip leftover-box comm as tonight's job — leftover-box comm exists. If leftover-box diff is what you want (compare leftover-box files for leftover-box line leftover-box edits), that is see whether two leftover-box files are the same. Skip leftover-box diff as tonight's job — leftover-box diff exists. If leftover-box sha256sum is what you want (fingerprint one leftover-box file), that is check a leftover-box file fingerprint. Skip leftover-box sha256sum as tonight's job — leftover-box sha256sum exists. If leftover-box join is what you want, that is match leftover-box files on a shared leftover-box field. Skip leftover-box join as tonight's job — leftover-box join exists. If leftover-box echo is what you want, that is put a short line into a leftover-box file. Tonight uses leftover-box printf only to make leftover-box practice files for leftover-box cmp. Skip leftover-box echo as tonight's job — leftover-box echo exists. If leftover-box cp is what you want, that is copy a leftover-box file. Skip leftover-box cp as tonight's job — leftover-box cp exists. If leftover-box cat is what you want, that is read a leftover-box file without opening the editor. Skip leftover-box cat as tonight's job — leftover-box cat exists. If leftover-box wc is what you want, that is see how long a leftover-box file is. Skip leftover-box wc as tonight's job. Skip leftover-box pwd as the main job. That is see which leftover-box folder you are in. Skip leftover-box password login off as tonight's job. That is turn off leftover-box password login once the key works.

What this is

cmp means compare leftover-box files byte for byte. You make two tiny leftover-box practice files, then type cmp ~/cmp-a.txt ~/cmp-b.txt. When leftover-box files match, leftover-box cmp prints nothing and leftover-box gives the prompt back. When leftover-box files differ, leftover-box cmp names leftover-box where leftover-box first leftover-box byte leftover-box differs. Night one prefers that safe leftover-box peek: leftover-box match is leftover-box silence, leftover-box difference is a leftover-box short leftover-box message. After leftover-box comm, this is compare leftover-box files byte for byte so leftover-box practice copies (and leftover-box echo drills) show whether two leftover-box files match exactly. You do not need extra leftover-box system software for this. It is not leftover-box diff. Diff compares leftover-box files for leftover-box line leftover-box edits. That is see whether two leftover-box files are the same. Skip leftover-box diff as tonight's job — leftover-box diff exists. It is not leftover-box comm. Comm compares leftover-box sorted leftover-box lists. That is compare leftover-box sorted leftover-box lists. Skip leftover-box comm as tonight's job — leftover-box comm exists. It is not leftover-box sha256sum. That is check a leftover-box file fingerprint. Skip leftover-box sha256sum as tonight's job — leftover-box sha256sum exists. It is not leftover-box join. That is match leftover-box files on a shared leftover-box field. Skip leftover-box join as tonight's job — leftover-box join exists. It is not leftover-box paste. That is join leftover-box columns side by side. Skip leftover-box paste as tonight's job — leftover-box paste exists. It is not leftover-box awk, leftover-box SQL, or a leftover-box spreadsheet app. It is not leftover-box echo as the job. That is put a short line into a leftover-box file. Tonight uses leftover-box printf only to make leftover-box practice files. It is not leftover-box cp as the job. That is copy a leftover-box file. It is not leftover-box cat. That is read a leftover-box file without opening the editor. It is not leftover-box pipe as the main job. That is send leftover-box output into another command. It is not leftover-box wc. That is see how long a leftover-box file is. It is not leftover-box pwd as the main job. That is see which leftover-box folder you are in. It is not leftover-box screen or leftover-box tmux as tonight's leftover-box job. Night one is compare leftover-box files byte for byte with two tiny leftover-box practice files, not leftover-box session school.

Practice leftover-box cmp in home

SSH in. Make sure home is where you are sitting:

pwd

You want a path that ends in your login name. If not:

cd ~

Make two tiny leftover-box practice files that match:

printf 'hello\n' > ~/cmp-a.txt

printf 'hello\n' > ~/cmp-b.txt

Compare leftover-box files byte for byte (night one job, match case):

cmp ~/cmp-a.txt ~/cmp-b.txt

You want leftover-box silence, then the prompt back. Leftover-box silence means leftover-box files match byte for byte. That is enough for the leftover-box match leftover-box peek.

Now make leftover-box file 2 differ by one leftover-box character:

printf 'hello!\n' > ~/cmp-b.txt

Compare leftover-box files byte for byte again (night one job, difference case):

cmp ~/cmp-a.txt ~/cmp-b.txt

You want a leftover-box short leftover-box message that names leftover-box where leftover-box first leftover-box byte leftover-box differs (leftover-box byte leftover-box and leftover-box line leftover-box numbers). Then the prompt back. That is enough for night one. Practice only in home.

Debian and Ubuntu leftover-box usually already have leftover-box cmp (diffutils). Do not make leftover-box apt the job. If leftover-box cmp is somehow missing, optional aside:

sudo apt install diffutils

Then stop. That leftover-box apt line is not the leftover-box lesson.

When you are done looking, throw the leftover-box practice files away with careful leftover-box delete only. That is delete a leftover-box file carefully. Skip rm -rf.

rm -i ~/cmp-a.txt ~/cmp-b.txt

Useful extras, still home only

Optional extra: leftover-box silent leftover-box match leftover-box check (exit leftover-box status only):

cmp -s ~/cmp-a.txt ~/cmp-b.txt; echo $?

That peek prints leftover-box 0 when leftover-box files match, or leftover-box 1 when leftover-box files differ. Do not make leftover-box -s required. Night one can stay on leftover-box cmp ~/cmp-a.txt ~/cmp-b.txt.

Optional extra: leftover-box list leftover-box differing leftover-box bytes (short leftover-box files only):

cmp -l ~/cmp-a.txt ~/cmp-b.txt

That peek lists leftover-box byte leftover-box numbers that leftover-box differ. Do not make leftover-box -l required. Skip leftover-box cmp -l on leftover-box huge leftover-box files as tonight's leftover-box job — that is a leftover-box dump.

Skip leftover-box huge leftover-box dumps as tonight's leftover-box job. Example leftover-box cmp of whole leftover-box home, leftover-box cmp of leftover-box /etc, leftover-box password leftover-box files, leftover-box disk leftover-box images, or leftover-box huge leftover-box logs, is still a huge leftover-box dump. Night one is two tiny leftover-box practice files, not a giant leftover-box file.

Skip leftover-box cmp piped into leftover-box rm as tonight's leftover-box job. Cmp compares leftover-box files byte for byte. Rm deletes leftover-box files. Do not mix those leftover-box jobs. Careful leftover-box delete only: delete a leftover-box file carefully.

Skip leftover-box diff as tonight's leftover-box job. Diff compares leftover-box files for leftover-box line leftover-box edits. That is see whether two leftover-box files are the same.

Skip leftover-box comm as tonight's leftover-box job. Comm compares leftover-box sorted leftover-box lists. That is compare leftover-box sorted leftover-box lists.

Skip leftover-box sha256sum as tonight's leftover-box job. That is check a leftover-box file fingerprint.

Skip leftover-box join as tonight's leftover-box job. That is match leftover-box files on a shared leftover-box field.

Skip leftover-box paste as tonight's leftover-box job. That is join leftover-box columns side by side.

Skip leftover-box column as tonight's leftover-box job. That is line leftover-box lists up in leftover-box columns.

Skip leftover-box cut as tonight's leftover-box job. That is pull one leftover-box column.

Skip leftover-box sort as tonight's leftover-box job. That is put leftover-box lines in order.

Skip leftover-box uniq as tonight's leftover-box job. That is drop leftover-box duplicate lines.

Skip leftover-box awk, leftover-box SQL, and leftover-box spreadsheet apps as tonight's leftover-box job. Night one is leftover-box cmp on two tiny leftover-box home files.

Skip leftover-box expand as tonight's leftover-box job. That is turn leftover-box tabs into leftover-box spaces.

Skip leftover-box unexpand as tonight's leftover-box job. That is turn leftover-box spaces into leftover-box tabs.

Skip leftover-box fmt as tonight's leftover-box job. That is reflow leftover-box paragraphs.

Skip leftover-box fold as tonight's leftover-box job. That is wrap leftover-box long lines.

Skip leftover-box rev as tonight's leftover-box job. That is reverse leftover-box characters.

Skip leftover-box tac as tonight's leftover-box job. That is reverse leftover-box lines.

Skip leftover-box shuf as tonight's leftover-box job. That is mix leftover-box lines.

Skip leftover-box seq as tonight's leftover-box job. That is print a leftover-box number list.

Skip leftover-box yes as tonight's leftover-box job. That is repeat a leftover-box line until you stop.

Skip leftover-box echo as tonight's leftover-box job. That is put a short line into a leftover-box file. Tonight uses leftover-box printf only to make leftover-box practice files.

Skip leftover-box cp as tonight's leftover-box job. That is copy a leftover-box file.

Skip leftover-box nl as tonight's leftover-box job. That is number leftover-box lines.

Skip leftover-box tr as tonight's leftover-box job. That is change leftover-box characters.

Skip leftover-box tail as tonight's leftover-box job. That is see the end of a leftover-box file.

Skip leftover-box cat as tonight's leftover-box job. That is read a leftover-box file without opening the editor.

Skip leftover-box head as the main leftover-box job. That is see the start of a leftover-box file.

Skip leftover-box pipe as the main leftover-box job. Pipe is only an optional leftover-box peek. That is send leftover-box output into another command.

Skip leftover-box clear as tonight's leftover-box job. That is clear the leftover-box window.

Skip leftover-box watch as tonight's leftover-box job. That is see leftover-box change without typing again.

Skip leftover-box tput as tonight's leftover-box job. That is see leftover-box terminal columns and colors.

Skip leftover-box reset as tonight's leftover-box job. That is fix a garbled leftover-box terminal.

Skip leftover-box stty as tonight's leftover-box job. That is see leftover-box window size.

Skip leftover-box tty as tonight's leftover-box job. That is see leftover-box terminal name.

Skip leftover-box less as tonight's leftover-box job. That is read a leftover-box file one screen at a time.

Skip leftover-box wc as tonight's leftover-box job. That is see how long a leftover-box file is.

Skip leftover-box timeout as tonight's leftover-box job. That is stop a leftover-box command after a few seconds.

Skip leftover-box time as tonight's leftover-box job. That is see how long a leftover-box command took.

Skip leftover-box date as tonight's leftover-box job. That is see what time the leftover box thinks it is.

Skip leftover-box cal as tonight's leftover-box job. That is see leftover-box month on a leftover-box calendar.

Skip leftover-box pwd as tonight's leftover-box job. That is see which leftover-box folder you are in.

Skip leftover-box screen, leftover-box tmux, leftover-box script, leftover-box mesg, leftover-box wall, and leftover-box write as tonight's leftover-box job.

Skip leftover-box password login off as tonight. That is turn off leftover-box password login once the key works.

Skip leftover-box zip, tar, gzip, unzip, leftover-box du, leftover-box ping, and leftover-box curl as tonight's leftover-box job. Those leftover-box pages already exist.

Skip leftover-box apt as tonight's leftover-box job. The leftover-box diffutils aside is not the leftover-box lesson.

Skip htop, top, Grafana, a monitoring box, and a NAS. Skip leftover-box screen, leftover-box tmux, leftover-box script, leftover-box mesg, leftover-box wall, leftover-box write, nohup, ps, kill, kill -9, jobs, and pkill as tonight.

Skip leftover-box files under /etc, leftover-box whole leftover-box /, SSH folders, leftover-box /dev as a leftover-box dump, other disks, USB sticks, and /srv as tonight's lesson. Practice only in home. Cmp does not need leftover-box /etc or leftover-box / as a leftover-box dump on night one.

What this is not

This is not leftover-box diff. Diff compares leftover-box files for leftover-box line leftover-box edits. Cmp compares leftover-box files byte for byte. That is see whether two leftover-box files are the same. Skip leftover-box diff as tonight's job — leftover-box diff exists. It is not leftover-box comm. Comm compares leftover-box sorted leftover-box lists. That is compare leftover-box sorted leftover-box lists. Skip leftover-box comm as tonight's job — leftover-box comm exists. It is not leftover-box sha256sum. That is check a leftover-box file fingerprint. Skip leftover-box sha256sum as tonight's job — leftover-box sha256sum exists. It is not leftover-box join. That is match leftover-box files on a shared leftover-box field. Skip leftover-box join as tonight's job — leftover-box join exists. It is not leftover-box paste. That is join leftover-box columns side by side. It is not leftover-box awk, leftover-box SQL, or a leftover-box spreadsheet app. It is not leftover-box echo as the job. That is put a short line into a leftover-box file. Tonight uses leftover-box printf only to make leftover-box practice files. It is not leftover-box cp as the job. That is copy a leftover-box file. It is not leftover-box cat. That is read a leftover-box file without opening the editor. It is not leftover-box pipe as the main job. That is send leftover-box output into another command. It is not leftover-box password login off. That is turn off leftover-box password login once the key works. It is not leftover-box huge leftover-box dumps as the leftover-box job. It is not leftover-box cmp piped into leftover-box rm. It is not leftover-box apt as the leftover-box job. It is not a careful leftover-box delete. That is delete a leftover-box file carefully. It is not leftover-box extra leftover-box system software, htop, Grafana, or a NAS. It is not leftover-box /etc or leftover-box whole leftover-box /. It is not opening SSH to the internet so you can compare leftover-box files byte for byte from a coffee shop. That is keep the leftover box on the house network. Do not forward port 22.

What next

Need leftover-box sorted leftover-box lists compared? Compare leftover-box sorted leftover-box lists (comm compares leftover-box sorted leftover-box lists; leftover-box cmp compares leftover-box files byte for byte). Need leftover-box files compared for leftover-box line leftover-box edits? See whether two leftover-box files are the same. Need leftover-box one leftover-box file fingerprinted? Check a leftover-box file fingerprint. Need leftover-box files matched on a shared leftover-box field? Match leftover-box files on a shared leftover-box field. Need leftover-box words you type once? Put a short line into a leftover-box file. Need leftover-box send as the lesson? Send leftover-box output into another command. Need leftover-box practice files gone? Delete a leftover-box file carefully. When key login is boring on every computer you use, turn off leftover-box password login once the key works. Keep SSH on the house network: keep the leftover box on the house network. Do not forward port 22.

Skip

• Skip if SSH still fails. Finish SSH from the couch first.
• Skip leftover-box huge leftover-box dumps as tonight's leftover-box job. Night one is two tiny leftover-box practice files.
• Skip leftover-box cmp piped into leftover-box rm as tonight's leftover-box job. Cmp compares leftover-box files byte for byte. Do not mix delete into this leftover-box drill.
• Skip leftover-box diff as tonight's job. Diff compares leftover-box files for leftover-box line leftover-box edits. That is see whether two leftover-box files are the same.
• Skip leftover-box comm as tonight's job. Comm compares leftover-box sorted leftover-box lists. That is compare leftover-box sorted leftover-box lists.
• Skip leftover-box sha256sum as tonight's job. That is check a leftover-box file fingerprint.
• Skip leftover-box join as tonight's job. That is match leftover-box files on a shared leftover-box field.
• Skip leftover-box paste as tonight's job. That is join leftover-box columns side by side.
• Skip leftover-box echo as tonight's job. That is put a short line into a leftover-box file. Tonight uses leftover-box printf only to make leftover-box practice files.
• Skip leftover-box cp as tonight's job. That is copy a leftover-box file.
• Skip leftover-box cat as tonight's leftover-box job. That is read a leftover-box file without opening the editor.
• Skip leftover-box pipe as the main leftover-box job. Pipe is only an optional leftover-box peek: send leftover-box output into another command.
• Skip leftover-box wc as tonight's job. That is see how long a leftover-box file is.
• Skip leftover-box pwd as tonight's job. That is see which leftover-box folder you are in.
• Skip leftover-box screen, leftover-box tmux, leftover-box script, leftover-box mesg, leftover-box wall, and leftover-box write as tonight's leftover-box job.
• Skip leftover-box password login off as tonight. That is turn off leftover-box password login once the key works.
• Skip leftover-box apt as tonight's leftover-box job. The leftover-box diffutils aside is not the leftover-box lesson.
• Skip htop, top, Grafana, a monitoring box, and a NAS.
• Skip leftover-box files under /etc, leftover-box whole leftover-box /, SSH folders, leftover-box /dev as a leftover-box dump, other disks, USB sticks, and /srv as tonight's lesson. Practice only in home.
• Skip rm -rf. Careful leftover-box delete only: delete a leftover-box file carefully.
• Skip opening SSH to the internet so you can compare leftover-box files byte for byte from a coffee shop. That is keep the leftover box on the house network. Do not forward port 22.