How to Copy, move, rename, and remove files in Linux
< Copying >
To copy files, you use the cp command. The following will copy file to file2. Note that if file2 doesn't exist, it'll be created, but if it exists, it'll be overwritten:
$ cp file file2
There aren't any undo commands in the Linux CLI, so accidentally overwriting an important file would probably make you pull your head off. The risk of doing so is smaller if you use the -i option ("interactive") with cp. The following does the same as the above, but if file2 exists, you'll be prompted before overwriting:
$ cp -i file file2
cp: overwrite `file2'? n
$
So it's a good idea to use the -i option whenever you're dealing with important files you don't want to lose!
If you want to copy file into directory dir1:
$ cp file dir1
The following would do the same as the above, copy file into dir1, but under a different name:
$ cp file dir1/file2
You can also copy multiple files into one directory with a single command:
$ cp file1 file2 file3 dir1
Note that if the last argument isn't a directory name, you'll get an error message complaining about it.
< Moving and renaming >
The mv command can be used for moving or renaming files. To rename a file, you can use it like this:
$ mv file file2
If file2 doesn't exist, it'll be created, but if it exists, it'll be overwritten. If you want to be prompted before overwriting files, you can use the -i option the same way as with cp:
$ mv -i file file2
mv: overwrite `file2'? y
$
To move the file into another directory:
$ mv file dir1
If you want to rename the file to file2 and move it into another directory, you probably already figured out the command:
$ mv file dir1/file2
< Removing files >
The rm command is used for removing files and directories. To remove a file:
$ rm file
If you use the -i option, you'll be prompted before removing the file:
$ rm -i file
You can also delete more files at once:
rm file1 file2
Be careful with the rm command! As I already told you, Linux doesn't have any undo commands, and it doesn't put files into Trash where you can save them later. Once you've deleted a file.
Ubuntu, fedora, centos, linux
Remove all characters except letters and numbers from a string
If you insert a new value to a MySQL database, and the id is an auto_increment, this simple function will obtain the id for you without having to do a new query on the database. This is the easiest way to get the id from a newly added row using a MySQL insert query without having to do a second query.
<?php
$string = "This is some text and numbers 12345 and symbols !£$%^&";
$new_string = ereg_replace("[^A-Za-z0-9]", "", $string);
echo $new_string
?>