I want to make my Bash scripts more elegant for the end user. How do I hide the output when Bash is executing commands?
For example, when Bash executes
yum install nano
The following will show up to the user who executed the Bash:
Loaded plugins: fastestmirror
base | 3.7 kB 00:00
base/primary_db | 4.4 MB 00:03
extras | 3.4 kB 00:00
extras/primary_db | 18 kB 00:00
updates | 3.4 kB 00:00
updates/primary_db | 3.8 MB 00:02
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package nano.x86_64 0:2.0.9-7.el6 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
nano x86_64 2.0.9-7.el6 base 436 k
Transaction Summary
================================================================================
Install 1 Package(s)
Total download size: 436 k
Installed size: 1.5 M
Downloading Packages:
nano-2.0.9-7.el6.x86_64.rpm | 436 kB 00:00
warning: rpmts_HdrFromFdno: Header V3 RSA/SHA256 Signature, key ID c105b9de: NOKEY
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
Importing GPG key 0xC105B9DE:
Userid : CentOS-6 Key (CentOS 6 Official Signing Key) <[email protected]>
Package: centos-release-6-4.el6.centos.10.x86_64 (@anaconda-CentOS-201303020151.x86_64/6.4)
From : /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Installing : nano-2.0.9-7.el6.x86_64 1/1
Verifying : nano-2.0.9-7.el6.x86_64 1/1
Installed:
nano.x86_64 0:2.0.9-7.el6
Complete!
Now I want to hide this from the user and instead show:
Installing nano ......
How can I accomplish this task? I will definitely help to make the script more user friendly. In case an error occurs then it should be shown to the user.
I would like to know how to show same message while a set of commands are being executed.
You can redirect stdout to /dev/null.
yum install nano > /dev/null
Or you can redirect both stdout and stderr,
yum install nano &> /dev/null.
But if the program has a quiet option, that's even better.
A process normally has two outputs to screen: stdout (standard out), and stderr (standard error).
Normally informational messages go to sdout, and errors and alerts go to stderr.
You can turn off stdout for a command by doing
MyCommand >/dev/null
and turn off stderr by doing:
MyCommand 2>/dev/null
If you want both off, you can do:
MyCommand 2>&1 >/dev/null
The 2>&1 says send stderr to the same place as stdout.
You can redirect the output to /dev/null. For more info regarding /dev/null read this link.
You can hide the output of a comand in the following ways :
echo -n "Installing nano ......"; yum install nano > /dev/null; echo " done.";
Redirect the standard output to /dev/null, but not the standard error. This will show the errors occurring during the installation, for example if yum cannot find a package.
echo -n "Installing nano ......"; yum install nano &> /dev/null; echo " done.";
While this code will not show anything in the terminal since both standard error and standard output are redirected and thus nullified to /dev/null.
You should not use bash in this case to get rid of the output. Yum does have an option -q which suppresses the output.
You'll most certainly also want to use -y
echo "Installing nano..."
yum -y -q install nano
To see all the options for yum, use man yum.
.SILENT:
Type " .SILENT: " in the beginning of your script without colons.
>/dev/null 2>&1 will mute both stdout and stderr
yum install nano >/dev/null 2>&1
Source: Stackoverflow.com