Move a file and leave a soft link behind

Question

I'm looking for a single linux command that allows me to do the equivalent of this:

cp /some/path/file /another/path/ && ln -sf /another/path/file /some/path/

If there isn't one, what's the best way to do this for a bunch of files?

I don't know Bash scripting well enough to write it, but my solution would be to just write a script and call it something catchy like cpln — Unkwntech, May 14 '09 at 08:33
To be safe you should use a `;` instead of `&&`. With `&&`, there is no guarantee that `ln` won't replace the original file with a soft link before `cp` has proceeded to read the file. You should also check the return value of `cp` in order to not write the file over with `ln` if the copy fails. — HelloGoodbye, May 07 '15 at 11:13
@HelloGoodbye You're confusing `&&` with `&`. As written, the line does check the return value of cp and only runs the second part if it succeeded. — itsadok, May 10 '15 at 12:33
The best answer to this question is here: http://unix.stackexchange.com/a/228166/7000 — Sridhar Sarnobat, Dec 30 '16 at 16:06

Mr Shark · Accepted Answer · 2012-12-10T10:12:28.713

7

A small note, is that you could use ln both times to make the command not actually move the data (assuming both paths are on the same filesystem).

ln /some/path/file /another/path/ && ln -sf /another/path/file /some/path/

But I assume that you want to move the content of /some/path/ to an other disk, and then create links to the new files so "no one" notices.

for f in `ls /some/path/`; do ln /some/path/$f /another/path/ && ln -sf /another/path/$f /some/path; done

Wrapping it in a bash function:

function cpln {
    for f in `ls $1`
    do
        ln $1/$f $2 && ln -sf $2/$f $1
    done
}

edited Dec 10 '12 at 10:12

answered May 14 '09 at 11:41

Mr Shark

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Is there a way to make this work if what I'm moving happens to be a directory? – tladuke Aug 09 '12 at 18:50
How does this move the actual file on disk? – Ibrahim Dec 06 '12 at 10:55
Ibrahim: the data doesn't move, it just updates the pointers in the directory. – Mr Shark Dec 10 '12 at 10:13
tladuke: Yes and no. Since the directory is much smaler on disk, there is no need for the ln trick (which don't work for directorys), just do a mv :-) – Mr Shark Dec 10 '12 at 10:16

score 2 · Answer 2 · edited Feb 26 '12 at 19:49

2

Theres my script you could use (takes two parameters /some/path/file and /another/path/ ):

#!/bin/bash
cp $1 $2
if [ "$?" -ne "0" ]; then
    echo "Some error"
    exit 1
    fi
ln -sf $2/${1##*/} ${1%/*}

edited Feb 26 '12 at 19:49

Wayne Arthurton

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11

answered May 14 '09 at 11:29

Kazimieras Aliulis

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Cool trick with the string manipulations, never saw that before. Thanks! – itsadok May 17 '09 at 11:17

score 1 · Answer 3 · answered May 14 '09 at 11:28

1

Seriously, I thought this was a really easy question.

Here's what I can do in perl:

#!/bin/perl
# Usage: cpln TARGETDIR SOURCE...
# Example: find tree/ -type f | xargs cpln commands/

$target = shift;

foreach(@ARGV) {
    m[(.*)/([^/]+)];
    system("cp $_ $target");
    system("ln -sf $target/$2 $1/");
}

I was hoping for something more elegant, but I guess I'll use that.

answered May 14 '09 at 11:28

itsadok

1,839
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1

To do it "in Perl," you should use File::Copy (or similar) and symlink(). Perl is not shell; avoid system(), and *especially* avoid passing whole command lines to system() (e.g., what if an argument contains a space?). Either way, always, always, ALWAYS check return values. – John Siracusa May 14 '09 at 14:53

Move a file and leave a soft link behind

3 Answers3