Annotated edit history of
IORedirectionNotes version 9, including all changes.
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BenStaz |
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!Append to a file owned by root |
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In this example I will use the ''sources.list'' file that contains a list of the repositories from which we can get packages. |
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Firstly: |
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*sudo echo "#TEST REPOSITORY" >> /etc/apt/sources.list |
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LawrenceDoliveiro |
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results in a "Permission denied error". This is because the ''>> /etc/apt/sources.list'' redirection is processed by your shell _before_ spawning <tt>sudo</tt>, so it is trying to open the file with your (ordinary) user privileges, not root privileges. |
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BenStaz |
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BenStaz |
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Ways around this: |
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1) |
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BenStaz |
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*sudo bash -c 'echo "#TEST REPOSITORY" >> /etc/apt/sources.list' |
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BenStaz |
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LawrenceDoliveiro |
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The shell spawned by <tt>sudo</tt> reads its command from the string after the ''-c'' switch, so the redirection is done in a process which is already running as root. |
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BenStaz |
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2) |
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*echo "#TEST REPO" | sudo tee -a /etc/apt/sources.list |
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LawrenceDoliveiro |
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The 'tee' command reads from standard input and the ''-a'' switch appends it to the file. Again, the file is opened by the process spawned by <tt>sudo</tt>, which is running as root. |
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BenStaz |
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3) |
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*sudo tee -a /etc/apt/sources.list <<< "#TEST REPO" |
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LawrenceDoliveiro |
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An alternative formulation of 2), using a [HereString|HereStrings]. |
