Shorter way to assign a default value to the standard output stream

Question

I have this code :

tr ' ' '\n'|sort -n|head -1

The code is pretty simple, it takes a list of integer in the standard input stream (like 5 9 8 7 5 2 -12 -30), it sort the integers and display only the first integer. But i need to ouput 0 if the given list is empty. And i can't find a short way to that. I have a solution with a ternary operator and a echo 0, but i feel i can do far better. I just need to replace the input stream by 0 if this stream is empty.

Sidenote : I don't need to call read to get the user input. The program is called with the input stream directly like cmd < 1 5 6 -20 45

Here my current code :

read l
[ -n "$l" ]&&echo $l|tr ' ' '\n'|sort -n|head -1||echo 0

Answer 1

34 bytes

a=($(tr \  \\n|sort -n))
echo $[a]

The first line saves the sorted input values in an array a.

This avoids using head -1, since referencing the array as $a will yield its first value.

The second line uses a in the arithmetic expansion $[a]. In this context, an empty string is interpreted as 0.

For a different default value, parameter substitution could be used instead. For example, the last line could become

echo ${a:-puppies}

Answer 2

37 33 32 bytes

tr \  \\n|sort -n|sed s/^$/0/\;q

Edit: Saved 4 bytes thanks to @DigitalTrauma.

Answer 3

42 bytes

Two different ways that have the same byte-count Use awk as the last command

tr ' ' '\n'|sort -n|awk 'NR==1{print $1+0}'

Or do all the computations in awk

awk -v RS=" " '{m=m>$1?m:$1}END{print m+0}'

Answer 4

Pure bash: 41 bytes.

No requirement of any tr, sort, head...

t=${1:-0};for i;{ ((t=i<t?i:t));};echo $t

In a function you could use local -i for integer variables:

f() { local -i t=$1;for i;{ ((t=i<t?i:t));};echo $t;}

Then

f 5 9 8 7 5 2 -12 -30
-30

f
0

Note: If you need to read them from stdin

read l
f $l

will do the job.

As:

read l;for i in ${l:-0};{ ((t=i<t?i:t));};echo $t;}

Another version 58 bytes.

Something longer, but could be quicker, as there is no loop.

. <(printf v[%d+99**9]=\  $@);v=(${!v[@]});echo $[v-99**9]

In a function:

f() { local v;. <(printf v[%d+99**9]=\  $@)
      v=(${!v[@]});echo $[v-99**9];}

Then

f 34 56 1000 12  -156 53 -12 -21 321 3221
-156

f
0