sudo cat << EOF > File doesn't work, sudo su does
BashShellSudoBash Problem Overview
I tried the following on the command prompt in bash:
sudo cat << EOF > /etc/yum.repos.d/some-name.repo
#Content
#....
#...
EOF
It complained :
-bash: /etc/yum.repos.d/some-name.repo: Permission denied
Then I did sudo su and tried the exact same thing except the sudo before cat, and it worked without any problem. What am I missing in the above ?
Bash Solutions
Solution 1 - Bash
Output redirection (e.g., >) is performed by bash, not by cat, while running with your UID. To run with root's UID use sudo:
sudo bash -c 'cat << EOF > /etc/yum.repos.d/some-name.repo
line1
line2
line3
EOF'
Solution 2 - Bash
Another option is tee.
cat << EOF | sudo tee -a /etc/yum.repos.d/some-name.repo
...
EOF
Solution 3 - Bash
As a variation to @Yuriy Nazarov's answer, only the piped output needs to be elevated thru sudo. The piped input can stay un-elevated:
sudo bash -c 'cat > /etc/yum.repos.d/some-name.repo' << EOF
line1
line2
line3
EOF
This means a much smaller portion of the command needs to be quoted and sent thru to sudo.
Solution 4 - Bash
As others have pointed out the shell redirection is done by the current shell not by cat. sudo only changes the permission of the program that is executed not of the shell doing the redirect. My solution to this is to avoid the redirect:
sudo dd of=/etc/yum.repos.d/some-name.repo << EOF
Solution 5 - Bash
if you are using ' inside the text then you may use:
$ sudo bash -c "cat > /etc/postfix/mysql-virtual_forwardings.cf << EOF
user = mail_admin
password = password
dbname = mail
query = SELECT destination FROM forwardings WHERE source='%s'
hosts = 127.0.0.1
EOF
"
this is tested on google cloud's virtual server centos 7.0