Can I execute nested or chained commands in UNIX shell?

Question

Can I execute command within another command in UNIX shells?

If impossible, can I use the output of the previous command as the input of next command, as in:

command x then command y,

where in command y I want use the output of command x?

Answer 1

You can use the backquotes for this.

For example this will cat the file.txt

cat `echo file.txt`

And this will print the date

echo the date is `date`

The code between back-quotes will be executed and be replaced by its result.

Answer 2

You can do something like;

x=$(grep $(dirname "$path") file)

here dirname "$path" will run first and its result will be substituted and then grep will run, searching for the result of dirname in the file