Here is the code i wrote,when i execute the code,the terminal didn't output anything and the program is blocked

var util=require('util')
var exec=require('child_process').exec;
exec('iostat 5',function(err,stdout,stderr){
    util.puts("hello")
    util.puts(stdout)
})

If i change the exec mand like this: it works and outputs the file list

var util=require('util')
var exec=require('child_process').exec;
exec('ls -al',function(err,stdout,stderr){
    util.puts("hello")
    util.puts(stdout)
})

is there any diffent between a block mand(iostat) and nonbolck mand(ls)?

Here is the code i wrote,when i execute the code,the terminal didn't output anything and the program is blocked

var util=require('util')
var exec=require('child_process').exec;
exec('iostat 5',function(err,stdout,stderr){
    util.puts("hello")
    util.puts(stdout)
})

If i change the exec mand like this: it works and outputs the file list

var util=require('util')
var exec=require('child_process').exec;
exec('ls -al',function(err,stdout,stderr){
    util.puts("hello")
    util.puts(stdout)
})

is there any diffent between a block mand(iostat) and nonbolck mand(ls)?

• javascript
• node.js

Share Improve this question Follow edited Apr 8, 2012 at 9:06 drifting asked Apr 8, 2012 at 9:04 driftingdrifting 7111 gold badge22 silver badges55 bronze badges

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1 Answer 1

Sorted by: Reset to default 2

iostat 5 loops forever every 5 seconds and never terminates, so your exec callback will never be called. Instead you could call iostat from a setInterval call, or just remove the 5 if you only need it once.