name : pseudo-file.example # Pseudo file example # Mksquashfs supports pseudo files, these allow fake files, directories, # character and block devices to be specified and added to the Squashfs # filesystem being built, rather than requiring them to be present in the # source directories. # # This, for example, allows device nodes to be added to the filesystem without # requiring root access. # Mksquashfs 4.1 adds support for "dynamic pseudo files" and a modify operation. # Dynamic pseudo files allow files to be dynamically created when Mksquashfs # is run, their contents being the result of running a command or piece of # shell script. The modifiy operation allows the mode/uid/gid of an existing # file in the source filesystem to be modified. # Two Mksquashfs options are supported, -p allows one pseudo file to be # specified #on the command line, and -pf allows a pseudo file to be specified # containing a list of pseduo definitions, one per line. # Pseudo file examples # Run mkquashfs . /tmp/img -pf pseudo-file.examples # to see their effect # Creating dynamic file examples # Create a file "dmesg" containing the output from dmesg. dmesg f 444 root root dmesg # Create a file RELEASE containing the release name, date, build host, and # an incrementing version number. The incrementing version is a side-effect # of executing the shell script, and ensures every time Mksquashfs is run a # new version number is used without requiring any other shell scripting. RELEASE f 444 root root \ if [ ! -e /tmp/ver ]; then \ echo 0 > /tmp/ver; \ fi; \ ver=`cat /tmp/ver`; \ ver=$((ver +1)); \ echo $ver > /tmp/ver; \ echo -n "release x.x"; \ echo "-dev #"$ver `date` "Build host" `hostname` # Copy 10K from the device /dev/sda1 into the file input. Ordinarily # Mksquashfs given a device, fifo, or named socket will place that special file # within the Squashfs filesystem, this allows input from these special # files to be captured and placed in the Squashfs filesystem. input f 444 root root dd if=/dev/sda1 bs=1024 count=10 # Creating a block or character device examples # Create a character device "chr_dev" with major:minor 100:1 and # a block device "blk_dev" with major:minor 200:200, both with root # uid/gid and a mode of rw-rw-rw. chr_dev c 666 root root 100 1 blk_dev b 666 0 0 200 200 # Creating a directory example # create a directory "pseudo_dir" with root uid/gid and mode of r--r--r--. pseudo_dir d 444 root root # Modifying attributes of an existing file exmaple # Change the attributes of the file "INSTALL" in the filesystem to have # root uid/gid and a mode of rw-rw-rw, overriding the attributes obtained # from the source filesystem. INSTALL m 666 root root