The rm Command
The rm command is probably one of the first commands you learned. Here we look at some options that may save you a lot of time. Before we get into the details, some words of warning. In the Unix tradition, Linux does not ask unnecessary questions. If you tell it to remove a file or a set of files, it will do just that. If you want it to ask you for confirmation, you will need to ask it to do that.
The basic syntax of rm is:
rm [options] filenames
The options must start with a -. One or more filenames can be specified, and wildcards are permitted (because the shell, not rm, expands them).
If you are not familiar with wildcards (* and ? to name the most dangerous), read up on them. Placing a wildcard character in the file name list by accident can make you a very unhappy camper.
rm is the command used, in Linux terminology, to unlink a file. What this means is that the directory entry for the file is removed. A side effect (and the effect that we generally expect) is that the file is deleted. But this may not be the case.
The Linux file system makes it possible for a file to have more than one name or directory entry. The ln command allows you to create these additional names or links. If these links are hard links, links created with the ln command without the -s option, you have a file that can be accessed by these multiple names.
By using the rm command on one of these names, you only delete the name, not the actual file. When the last name pointing to the file is removed, the file is finally removed.
Now that you know about the basics, there are a bunch of options that make it possible to do more than just remove a file. A handy option for the timid is -i. The -i stands for interactive. When specified, rm will prompt you before it deletes each file. If you respond with y or Y the file will be deleted, otherwise the delete will be skipped.
For example, if you enter:
rm -i dog cat pig
you will be prompted with:
rm: remove `dog'?
Pressing y or Y and <return> will cause the file dog to be deleted. No matter what you pressed, rm will then move along to the next file, in this case cat, and prompt again.
Normally, if rm encounters a file that you do not have write permission to, but you do have permission to modify the file's directory, it will ask for confirmation. You then enter y or Y followed by <return> to force the removal of the file. The -f option overrides this default behavior. If you specify -f, rm will do the removal without the prompt. This option also eliminates the error message that rm generally produces if a specified file is not found.
Now, the scary option, -r. The -r stands for recursive. If you specify a directory name and the -r option, rm will remove the specified directory and all its contents, including any subdirectories contained within it (and the subdirectories' files and subdirectories and so forth). For example, if you had a directory named Joe in your current directory which contained the files name address phone and a directory Other that contained the files ssn and age, you could delete each file individually with the following command:
rm Joe\name Joe\address Joe\phone Joe\Other\ssn\ Joe\Other\age
You could then use the rmdir command to remove the directories Other and Joe:
rmdir Joe/Other Joe
rm -r Joe
Finally, a trick. A common problem people run into is how to delete a file whose name starts with a -. For example, if you entered the command
in an attempt to remove a file named -garbagefile, you would get the error message:
rm: illegal option -g
Try rm -help for more information.
This is because rm assumes that if its first argument starts with a - it is an option. The solution is to use a name that does not confuse rm. For example, you can use either the full pathname of the file or a relative pathname where you explicitly specify the current directory using ./. Thus, the following command would do the job:
Phil Hughes is the publisher of Linux Journal.
Fast/Flexible Linux OS Recovery
On Demand Now
In this live one-hour webinar, learn how to enhance your existing backup strategies for complete disaster recovery preparedness using Storix System Backup Administrator (SBAdmin), a highly flexible full-system recovery solution for UNIX and Linux systems.
Join Linux Journal's Shawn Powers and David Huffman, President/CEO, Storix, Inc.
Free to Linux Journal readers.Register Now!
- Download "Linux Management with Red Hat Satellite: Measuring Business Impact and ROI"
- Petros Koutoupis' RapidDisk
- The Italian Army Switches to LibreOffice
- ServersCheck's Thermal Imaging Camera Sensor
- Linux Mint 18
- Oracle vs. Google: Round 2
- The FBI and the Mozilla Foundation Lock Horns over Known Security Hole
- Varnish Software's Varnish Massive Storage Engine
- Privacy and the New Math
Until recently, IBM’s Power Platform was looked upon as being the system that hosted IBM’s flavor of UNIX and proprietary operating system called IBM i. These servers often are found in medium-size businesses running ERP, CRM and financials for on-premise customers. By enabling the Power platform to run the Linux OS, IBM now has positioned Power to be the platform of choice for those already running Linux that are facing scalability issues, especially customers looking at analytics, big data or cloud computing.
￼Running Linux on IBM’s Power hardware offers some obvious benefits, including improved processing speed and memory bandwidth, inherent security, and simpler deployment and management. But if you look beyond the impressive architecture, you’ll also find an open ecosystem that has given rise to a strong, innovative community, as well as an inventory of system and network management applications that really help leverage the benefits offered by running Linux on Power.Get the Guide