CODEWITHSUNDEEP
bashshellxargs
user7858768
user7858768

Reputation: 1026

"ls | xargs" prints a single line while expecting there to be a line per file

I have the following directory:

> tree
.
├── a.txt
└── b.txt

> ls
a.txt   b.txt

When I run command ls | xargs echo I get the following:

> ls | xargs echo
a.txt b.txt

While I would have expected result to look something along the lines of

> ls | xargs echo
a.txt 
b.txt

Given that I am expecting xargs to process each file separately and echo to print each input on its own separate line.

Why the difference of expected vs actual?

As suggested I have tried:

find . -mindepth 1 -maxdepth 1 -exec echo {} \;

Which does work as expected and I presume allows other command to be subbed in for echo with -exec.

However, trying the other suggestions to try to get xargs working still does not work (prints the output on the same line).

Example:

printf "%s\n" * | xargs
a.txt b.txt

> find . -mindepth 1 -maxdepth 1 | xargs echo
./b.txt ./a.txt

Upvotes: 3

Views: 3374

Answers (1)

Timur Shtatland
Timur Shtatland

Reputation: 12377

Use find with -mindepth and -maxdepth options like so:

find . -mindepth 1 -maxdepth 1
# or:
find . -mindepth 1 -maxdepth 1 -exec echo {} \;

If you really must parse the output of ls (not the recommended practice, see the comments), use xargs with -n1 option:

ls | xargs -n1 echo

References:

Here is how to control which directories find searches, and how it searches them. These two options allow you to process a horizontal slice of a directory tree.

Option: -maxdepth levels

Descend at most levels (a non-negative integer) levels of directories below the command line arguments.
...
Option: -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the command line arguments.

find manual

--max-args=max-args
-n max-args
Use at most max-args arguments per command line.

xargs manual

Upvotes: 5

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