Command Line – Understanding the -alhF Flag in ls

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What is the -alhF flag in ls? I can't find it in the man page.

Best Answer

From man ls:

   -a, --all
          do not ignore entries starting with .

   -F, --classify
          append indicator (one of */=>@|) to entries

   -h, --human-readable
          with -l, print sizes in human readable format (e.g., 1K 234M 2G)

   -l     use a long listing format

The command ls -alhF is equivalent to ls -a -l -h -F

The ability to combine command line arguments like this is defined by POSIX.

Options that do not require arguments can be grouped after a hyphen, so, for example, -lst is equivalent to -t -l -s.

Related Solutions

What’s the purpose of `rm -P`

There is a technique called residual information retrieval that can read data that was deleted based on the idea that when the drive is magnetized in order to store data other parts that are close to the data is also affected by this and it should be possible to re-read data this way ... this is though a costly technique, but use it if you are paranoid ;)

By writing data 3 times (in this case) the parts next to the track on the drive should be re-set as well in order to make it impossible to re-read this way.

What’s the real point of the -f option on rm

I find that the man page lacks a little detail in this case. The -f option of rm actually has quite a few use cases:

To avoid an error exit code
To avoid being prompted
To bypass permission checks

You are right that it's pointless to remove a non-existent file, but in scripts it's really convenient to be able to say "I don't want these files, delete them if you find them, but don't bother me if they don't exist". Some people use the set -e in their script so that it will stop on any error (to avoid any further damage the script can cause), and rm -rf /home/my/garbage is easier than if [[ -f /home/my/garbage ]]; then rm -r /home/my/garbage; fi.

A note about permission checks: to delete a file, you need write permission to the parent directory, not the file itself. So let's say somehow there is a file owned by root in your home directory and you don't have sudo access, you can still remove the file using the -f option. If you use Git you can see that Git doesn't leave the write permission on the object files that it creates:

-r--r--r-- 1 phunehehe phunehehe 62 Aug 31 15:08 testdir/.git/objects/7e/70e8a2a874283163c63d61900b8ba173e5a83c

So if you use rm, the only way to delete a Git repository without using root is to use rm -rf.

Best Answer

Related Solutions

What’s the purpose of `rm -P`

What’s the real point of the -f option on rm

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