Is there any way to create backup copy of a file, without type its name twice?

Question

Often when I'm editing some system file first I create a backup copy. For example:

sudo cp /etc/ssh/sshd_config /etc/ssh/sshd_config.bak

Is there any simple 'shortcut' such as:

sudo cp /etc/ssh/sshd_config %s.bak

?

---

A workaround that I found is to use sed in this way:

sudo sed '' /etc/ssh/sshd_config -i.bak

Solution 1

You could use brace expansion like this:

cp example_file{,.bak}

Solution 2

1. What you asked for

You can create a small shellscript file bupper:

I have a directory ~/bin, where I keep such help files.

#!/bin/bash

if [ $# -eq 1 ]
then
 cp -pvi "$1" "${1}.bak"
else
 echo "Info:  $0 copies to a backup file"
 echo "Usage: $0 <file to be backed up with .bak extension>"
fi

Make it executable,

chmod ugo+x bupper

When in ~/bin, it will be in PATH and you can run it like any executable program anywhere (where you have write permissions).

Example:

$ bupper hello.txt 
'hello.txt' -> 'hello.txt.bak'
$ bupper hello.txt 
cp: overwrite 'hello.txt.bak'? n
$ bupper hello.txt 
cp: overwrite 'hello.txt.bak'? y
'hello.txt' -> 'hello.txt.bak'

2. Alternative - let the editor do the job automatically

Some editors have an option to create a backup copy of the file before you save a new version. This backup has often a tilde as the last character (tilde is the extension, but there is no dot before it).

Gedit, the standard editor in Ubuntu is one of them.

After setting gedit to save such a backup copy:

gedit hello.txt

And check afterwards

$ ls hello.txt*
hello.txt  hello.txt~  hello.txt.bak

Now hello.txt~ has been added to hello.txt and the backup created by bupper.

This works with nano too, with the option -B

nano -B hello.txt

so you can do it with a command line editor for 'sudo' tasks :-)

Comments

[George Udosen]

Oh, so nice! +1...

[pa4080]

Thank you for this answer. This was my first idea, but I must have script as this on every machine which I'm using.

[sudodus]

You beat me, very elegant :-)

[sudodus]

@pa4080, 75andyd's solution is elegant and portable (when you have learned it by heart). But I edited my answer to add a workaround - to let the editor do the job automatically. You can make Gedit create a backup file 'hello.txt' -> 'hello.txt~' and there are other editors that have the same option. This alternative is very convenient.

[shouldsee]

to be safer cp -n example_file{,.bak}

[hakre]

let (GNU) cp handle the backup: cp -v -f -b -T file{,} (also numbered backups are available)

[Victor S.]

to be even more safer cp -nv example_file{,.bak};

[Cymatical]

nano -B only seems to have one backup version ie notes.txt~