27 comment

1. Another way to do it:

   $ command &>/dev/null

2. Or you can close stdout and stderr for the command being executed:

   $ command 1>&- 2>&-

   1. Remember to add an additional & at the end of the statement to run the command in the background. Thank you Giuseppe for the tip.

   2. What do you mean by “close stdout and stderr” ?

      Thanks

3. Thanks! I was searching how resolve this problem, and your solution work perfect for me!

4. need a command in my bash script to remove some (not all) of the contents of directory2.
   The script does NOT run as root, which works because it removes the correct files but not the root-level stuff in directory2 (that I don’t want to remove).
   Problem is users get confused by the “permission denied” msgs output by the “rm”. So…
   I tried to redirect the stderror & stdout to /dev/null this way:
   rm * /directory1/directory2/ > 2&>1 /dev/null
   kept changing /dev/null form a special file & other users need crw-rw-rw-
   Will the recommended approaches allow me to redirect to /dev/null without messing it up for others?

   1. You could use find instead to filter out the files you don’t want to delete, or only delete files matching a patter:

      Delete all files except those with “attachments” in the name:
      # find . ! -name '*attachments*' -exec rm -v {} \;

      Delete all files with “attachments” in the name:
      # find . -name '*attachments*' -exec rm -v {} \;

      Find is very versitile, it’s pretty cool what you can acheive with find.

5. how does one redirect output from text file processing to a script file that uses the command line variable $1.

   file iplist has a long list of IP’s on the network and i need to send this to a script that creates a file with the ping info.

   script says: ping $1 > $1
   Please assist if possible

6. How reliable, if that’s the word I’m looking for, is ending a particular command in a script with a redirect like “2>/dev/null” ? What have folks’ experiences been with the different commands and bash/sh versions when trying it this way?

   I know it’s not recommended, but for someone like myself, with scripts they either run daily or don’t run for months and then go through a spate of executing them two and three times a day (only to go back to seldom running them until the next time it happens), it would be very convenient and not too too anxiety-producing to run a script and know that whatever passable or critical errors it comes up with are being suppressed.

   I’m much more inclined to put up with circumstances after the fact, and I seldom write anything that’s too destructive (on the system or OS/hardware install and performance level, at any rate) for a little error like Exiv2 complaining about some JPG file’s Photoshop IFD entry being out of bounds.

   So share up, coders and newbies. :)

   BZT

7. Thank you :))

8. Hi,
   how can I redirect output to /dev/null BUT errors on sdout.
   I mean: I want to launch a command:
   – if all goes good —> no output
   – if something goes wrong —> output of errors

   Thanks,
   Ciccio

9. ciccio –
   I think it would be the opposite of sending errors to the bucket.

   Something like:
   (your_command) 1>/dev/null
   should leave errors alone, that is, going to stout where you can see them. I’m sure you have something in mind where both good and bad output would normally go to stdout.

   BZT

10. ciccio, the order of the redirection counts.
    use:
    command 2>&1 1>/dev/null

    1. No, it does not matters. So following two are the same command:

       command 2>&1 1>/dev/null

       AND

       command 1>/dev/null 2>&1

       1. Hello,

          The order is important :

          $ ls non_existing_folder 1>/dev/null 2>&1

          (no output)

          $ ls non_existing_folder 2>&1 1>/dev/null
          ls: non_existing_folder: No such file or directory

11. echo “open 192.168.1.10 8080″| telnet | grep –color=auto “Connected to”
    gives the following output:
    ——————————————————-
    Connection closed by foreign host.
    Connected to 192.168.1.10 (192.168.1.10)
    ——————————————————-

    How can I get rid of “Connection closed by foreign host.” ?

    1. @smilyface

       you can close (omit) the stderr output from telnet command
       echo “open 192.168.1.10 8080″| telnet 2>&- | grep –color=auto “Connected to”

12. Hi

    I tried like below

    ping 127.0.0.1 > /dev/null 2>&1
    “but i am getting out as ” Ambiguous output redirect”
    Please suggest me

    1. Put in bash script:
       exec 2>/dev/null
       before your commands. And avoid redirection in the command itself.

13. l often do the following and I do not want an error (just a 0 length file)
    You get a valid output if the command works, otherwise the error is sent to /dev/null

    file=`ls doesthisfileexist 2>/dev/null`
    if [ -n $file ] ; then
    do something
    fi

    1. Why not:

       if [ ! -f $FILE ]
       then
           echo "File does not exist"
       fi
       

14. I just stumbled upon this article… FYI ‘command > /dev/null 2>&1` won’t work in every scenario. For example, this will still output an error message:

    ps -ef | grep | grep ps > /dev/null 2>&1

    1. Try:

       (ps -ef | grep | grep ps) > /dev/null 2>&1

       1. That is a pretty slick little trick. Didn’t know that one. Thanks!

15. How to get the error help in shell window

16. Thanks!
    Exactly what i wanted!

17. Hi,

    Please tell me how to redirect the output from a script to a log file so that i can save all the details which i am capturing in the script using read command.

    Here is a snippet of my code:
    echo “Enter the number”
    read $N > text
    ….

    If i open text in vi i am getting blank lines and i have saved my script as number.sh and done chmod on the script to give it user permissions as well.

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