Shell – What does the “ls -1” command do

lsosxshell

In my current directory, I execute the command:
ls -1 and it gives a list of the current directory contents.

In the same directory, I repeat the command: ls and it gives me the same result, with perhaps a different formatted output.

Finally, I try to find out about the available commands by typing ls --help and the output is:

usage: ls [-ABCFGHLOPRSTUWabcdefghiklmnopqrstuwx1] [file ...]

It looks like the last option is 1 (#1). Can someone explain what the ls -1 does and how it's different to the standard ls command?

Best Answer

Yes, the formatting of the output is the only difference between ls -1 and ls without any options.

From the ls manual on my system:

 -1      (The numeric digit "one".) Force output to be one entry per line.
         This is the default when output is not to a terminal.

This is also a POSIX option to the ls utility.

The manual for ls on your system is bound to say something similar (see man ls).

is piped ls the same as ls -1?

Related Solutions

Shell – file $(ls /usr/bin/* | grep zip) command gives me errors. What’s wrong

The error is coming because bash is trying to expand the * in your argument to ls using glob pattern matching. It will always through such an error when the glob doesn't match the pattern. The * then gets passed to ls as a real asterisk, which doesn't match a file either so ls will error!

There are several bits about what you are doing that are redundant. I know you are trying to learn a construct, but let's break down some of the bits of what you just accomplished and how it could have been done.

ls /usr/bin is sufficient to list files in the bin directory, you don't need the star at all.
You should never parse the output of ls at all, it is ambiguous and potentially dangerous.
You could get the same effect without grep by doing ls /usr/bin/*zip*, but the ls is still redundant, you can just pass the glob expantion to file: file /usr/bin/*zip*

Lastly, find is usually a better tool for finding files. You could do what you are after like this:

$ find /usr/bin -iname '*zip*' -exec file {} +

Strange Characters in ls Output – Redirecting ls Output to a File

Those "strange characters" are escape sequences for coloring the output.

This will print that number in blue color:

echo -e '\033[01;34m1010729039145\033[0m'

See man console_codes for more details.

You can tell ls in which cases it shall output colors:

   --color[=WHEN]
          colorize the output; WHEN can be 'never', 'auto', or 'always' (the default); more info below

Looks like your ls is actually an alias for ls --color=always. (Type type ls to verify.)

Usually ls --color=auto will do the right thing: It will print colors on screen but no into files.

If you really want the color in your file, your have to decide, if you want to see the actual escape sequences or the interpreted colors.

For example the less command will default to printing the actual sequences, but you can tell it to show the colors instead with the -R option:

   -R or --RAW-CONTROL-CHARS
          Like -r, but only ANSI "color" escape sequences are output in "raw" form.

Try less textfile vs. less -R textfile.

Best Answer

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Shell – file $(ls /usr/bin/* | grep zip) command gives me errors. What’s wrong

Strange Characters in ls Output – Redirecting ls Output to a File

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