How to fix Broken Pipe Error in Linux

Have you ever encountered a situation in which you were unable to download any package on your Linux machine ? Or you might have probably seen an error like package not installed? This kind of error can easily be fixed with a command like “sudo apt install –f”. On rare occasions, you may have experienced a broken pipe error.

A pipe in Linux / Unix connects two processes, one of them has read-end of the file and the other one has the write-end of the file. When a process writes to a Pipe, it gets stored in a buffer and gets retrieved by the other process. Broken pipe occurs when a process prematurely exits from either end and the other process has not yet closed the pipe.

Example use case:

A user has just recently reinstalled RVM (Ruby Version Manager) after he performed a fresh install of Ubuntu.

He then opened up the terminal and issued the command:

type rvm | head -1

This issued the following error:

rvm is a function -bash: type: write error: Broken pipe

What happened here is that when the user runs the command type rvm | head -1, bash has actually executed type rvm in one process and  head -1 in another process. The stdout of the type part is connected to the “write” end of a pipe whereas the stdin of the head part is hooked up to the “read” end. Note that the two processes have run concurrently ( at the same time ).

The head -1 process has carried out a read operation of data from stdin , then prints out a single line (as dictated by the -1 option) before exiting, causing  therefore the “read” end of the pipe to be closed. Since the rvm function has quite a long data stream (about 11 kB after having been bash parsed and reconstructed), which means that head exits yet at the same time type still has some data to write out (few KB).

Since type is trying to carry out a  write operation to a pipe whose other end has therefore been closed – a brokenpipe routine or the write() function that it invoked,  will return an EPIPE error which is known as “Broken pipe”.

Inspecting the Command

In most cases, this might not be the case but the first step you should check is whether the command issued was right or not. You should reissue the command and check whether it gets executed or not. You can also try issuing commands like “sudo apt update” and “sudo apt install –f” as these commands are not destructive in nature. If your problem still persists, try rebooting the machine and see whether the problem was resolved or not.

Fixing a Problem with File System

When you have issued the commands mentioned earlier multiple times and you still get the error, check whether the error reads something like “read-only file system” in the terminal output. This may be caused when your boot partition gets mounted as read-only for some reason. The problem could be caused by some faulty software installation when the system decides that it is not safe to write to the drive.

The other cause might be when you try to install something from apt and the installer needs to access some resource in read mode, but cannot perform the read operation properly. It may throw an error like “sudo: cannot mount”. This error occurs because most of the ‘entities’ in Linux are files and in order to read a resource, Linux would need to open that file and read it. If however another process is currently using that resource, then it may not be possible to read the file. Also, when the reading process exits abruptly and does not close the file, it may corrupt the file until the next boot.

If you still cannot access the files even after rebooting, then the problem could be bigger than anticipated. You may have a broken file system. To resolve this issue, you may need a stable Linux environment in order to work on the broken system. The best way to do this is to boot from a Live Linux USB drive and work from it.

This is the right moment to backup all your data. Although the following steps are safe, you should make sure to store your data on a secure device.

Once you boot into a Live USB drive you should start to check for the partitions with a corrupt file system. To do so, issue the following command:

sudo fsck.ext4 -fv /dev/sdaX”

Note that here X stands for the partition that you are trying to scan. Note that this command is for partitions of type ext4. If you have a partition of type ext3 or ext2 you will need to replace the command with “fsck.ext3” and “fsck.ext2” respectively. This will scan your drive and print the output on the terminal (note the -v flag). Alternatively, you can specify a -c flag to surface-scan the drive; it will look for bad sectors on the drive.

Once you have done this, your partition should hopefully been fixed. Now Boot into your machine and issue the command:

sudo mount -o rw,remount /

This will restore the read/write permission on your drive and will therefore solve the broken pipe issue.

Afterwords

You have just seen one solution to resolve the broken pipe issue, but a broken pipe is not a problem, it could be a symptom of a larger problem more often than not. You can have a broken pipe whenever you are trying to read a stream like resource that gets closed prematurely..

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