Simplified version of find(1) command.
This is college project aimed to get to know on parsing, ASTs, writing complex commands.
The following descriptions are from the Linux manual of find(1).
-P: Never follow symbolic links. This is the default behaviour. When find examines or prints information a file, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself.
-L: Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched.
-H: Cause the file information and file type returned for each symbolic link specified on the command line to be those of the file referenced by the link not the link itself. If the referenced file does not exist, the file information and type will be for the link itself. File information of all symbolic links not on the command line is that of the link itself.
-d (Free-BSD feature): Cause find to perform a depth-first traversal.
-group gname: File belongs to group gname.
-name pattern: Base of file name matches shell pattern pattern. Because the leading directories are removed, the file names considered for a match with -name will never include a slash, so `-name a/b' will never match anything.
-newer reference: Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used.
-perm mode: File's permission bits are exactly mode (octal).
-perm -mode: All of the permission bits mode are set for the file. (octal)
-perm /mode: Any of the permission bits mode are set for the file. (octal)
-type c
b block (buffered) special
c character (unbuffered) special
d directory
p named pipe (FIFO)
f regular file
l symbolic link; this is never true if the -L option is in effect
unless the symbolic link is broken.
s socket
-user uname: File is owned by user uname
-delete: Delete files; true if removal succeeded. If the removal failed, an error message is issued. If -delete fails, find's exit status will be 1.
-exec command: Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of ; is encountered. The string {} is replaced by the current file name being processed everywhere it occurs in the arguments to the command not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a \) or quoted to protect them from expansion by the shell.
-exec command {} +: This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of '{}' is allowed within the command, and (when find is being invoked from a shell) it should be quoted (for example, '{}') to protect it from interpretation by shells. The command is executed in the starting directory. If any invocation with the + form returns a non-zero value as exit status, then find returns a non-zero exit status.
-execdir command: Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files.
./myfind
./myfind -name foo
./myfind -type d
./myfind -perm 636
./myfind -exec echo {} \;