Bryan Geraghty

Traditional file system permissions management in Linux leaves most users wanting. Fortunately, there’s a feature that most linux users don’t even know about called ACLs and it’s most likely already available on your system. All you have to do to enable it is add the `acl` option to your volume in `/etc/fstab` and re-mount the volume.

Once that is done, here are some functions that I wrote to help manage these ACLs.

Here is an example of a command that grants apache permission to read a directory with these functions:

> source aclfunctions.bash; grantUserRead 'apache' /var/www '*';

aclfunctions.bash:

# Author :: Bryan Geraghty
# Date :: 2009-10-28
# Notes :: ACL management functions

##
# Resets permissions on all files and directories in the specified path and removes
# and ACL entries
#
# @param string $2 Base path Path in which all operations will take place
#
function resetAll
{
   echo "Resetting permissions on all files in directory $1";

   echo "Removing ACLs...";
   setfacl -Rb $1;

   echo "Resetting directories...";
   find $1 -type d -exec chmod 770 {} \;

   echo "Resetting files...";
   find $1 -type f -exec chmod 660 {} \;
}

##
# Grants read permissions to all files/folders with names matching $3, which reside
# inside of directory $2, to user $1.
#
# @param string $1 Username The user to whom read permissions will be granted
# @param string $2 Base path Path in which all operations will take place
# @param string $3 Target Name of the file/directory on which to set the permissions
#
function grantUserRead
{
   echo "Granting read permission to user $1 on files/folders named $3 in directory $2";

   ## Set the default permissions for new files on the specified directory
   echo "Setting defaults...";
   find $2 -name "$3" -type d -exec setfacl -d -m u:$1:rx {} \;

   ## Recusively set the permissions on all existing directories and files within the
   ## specified directory
   echo "Setting directory permissions...";
   find $2 -name "$3" -type d -exec setfacl -R -m u:$1:rx {} \;

   ## Grant permissions to any files with the specified name
   echo "Setting file permissions...";
   find $2 -name "$3" -type f -exec setfacl -m u:$1:r {} \;
}

##
# Grants write permissions to all files/folders with names matching $3, which reside
# inside of directory $2, to user $1.
#
# @param string $1 Username The user to whom read permissions will be granted
# @param string $2 Base path Path in which all operations will take place
# @param string $3 Target Name of the file/directory on which to set the permissions
#
function grantUserWrite
{
   echo "Granting write permission to user $1 on files/folders named $3 in directory $2";

   ## Set the default permissions for new files on the specified directory
   echo "Setting defaults...";
   find $2 -name "$3" -type d -exec setfacl -d -m u:$1:rwx {} \;

   ## Recusively set the permissions on all existing directories and files within the
   ## specified directory
   echo "Setting directory permissions...";
   find $2 -name "$3" -type d -exec setfacl -R -m u:$1:rwx {} \;

   ## Grant permissions to any files with the specified name
   echo "Setting file permissions...";
   find $2 -name "$3" -type f -exec setfacl -m u:$1:rw {} \;
}

##
# Grants read permissions to all files/folders with names matching $3, which reside
# inside of directory $2, to group $1.
#
# @param string $1 Group The user to whom read permissions will be granted
# @param string $2 Base path Path in which all operations will take place
# @param string $3 Target Name of the file/directory on which to set the permissions
#
function grantGroupRead
{
   echo "Granting read permission to group $1 on files/folders named $3 in directory $2";

   ## Set the default permissions for new files on the specified directory
   echo "Setting defaults...";
   find $2 -name "$3" -type d -exec setfacl -d -m g:$1:rx {} \;

   ## Recusively set the permissions on all existing directories and files within the
   ## specified directory
   echo "Setting directory permissions...";
   find $2 -name "$3" -type d -exec setfacl -R -m g:$1:rx {} \;

   ## Grant permissions to any files with the specified name
   echo "Setting file permissions...";
   find $2  -name "$3" -type f -exec setfacl -m g:$1:r {} \;
}

##
# Grants write permissions to all files/folders with names matching $3, which reside
# inside of directory $2, to group $1.
#
# @param string $1 Group The user to whom read permissions will be granted
# @param string $2 Base path Path in which all operations will take place
# @param string $3 Target Name of the file/directory on which to set the permissions
#
function grantGroupWrite
{
   echo "Granting write permission to group $1 on files/folders named $3 in directory $2";

   ## Set the default permissions for new files on the specified directory
   echo "Setting defaults...";
   find $2 -name "$3" -type d -exec setfacl -d -m g:$1:rwx {} \;

   ## Recusively set the permissions on all existing directories and files within the
   ## specified directory
   echo "Setting directory permissions...";
   find $2 -name "$3" -type d -exec setfacl -R -m g:$1:rwx {} \;

   ## Grant permissions to any files with the specified name
   echo "Setting file permissions...";
   find $2 -name "$3" -type f -exec setfacl -m g:$1:rw {} \;
}

##
# Grants execute permissions to all files/folders with names matching $3, which reside
# inside of directory $2, to user $1.
#
# @param string $1 Username The user to whom read permissions will be granted
# @param string $2 Base path Path in which all operations will take place
# @param string $3 Target Name of the file/directory on which to set the permissions
#
function grantUserExec
{
   echo "Granting execute permission to user $1 on files/folders named $3 in directory $2";

   ## Set the default permissions for new files on the specified directory
   echo "Setting defaults...";
   find $2 -name "$3" -type d -exec setfacl -d -m u:$1:rwx {} \;

   ## Recusively set the permissions on all existing directories and files within the
   ## specified directory. One command will siffice for files and directories when
   ## setting execute permissions
   echo "Setting directory and file permissions...";
   find $2 -name "$3" -exec setfacl -R -m u:$1:rwx {} \;
}

##
# Grants execute permissions to all files/folders with names matching $3, which reside
# inside of directory $2, to group $1.
#
# @param string $1 Group The user to whom read permissions will be granted
# @param string $2 Base path Path in which all operations will take place
# @param string $3 Target Name of the file/directory on which to set the permissions
#
function grantGroupExec
{
   echo "Granting execute permission to group $1 on files/folders named $3 in directory $2";

   ## Set the default permissions for new files on the specified directory
   echo "Setting defaults...";
   find $2 -name "$3" -type d -exec setfacl -d -m g:$1:rwx {} \;

   ## Recusively set the permissions on all existing directories and files within the
   ## specified directory. One command will siffice for files and directories when
   ## setting execute permissions
   echo "Setting directory and file permissions...";
   find $2 -name "$3" -exec setfacl -R -m g:$1:rwx {} \;
}