PHP Developer''''s Dictionary- P77 ppsx

PHP Developer’s Dictionary IT-SC book 380 bool posix_getcwd(string pathname, int mode); Description The posix_mkfifo() function creates a named pipe file specified by pathname with the mode specified by mode . posix_getgrnam() Syntax array posix_getgrnam(string name); Description The posix_getgrnam() function returns an associative array with information about the group defined in name . The associative array contains the entries listed in Table 9.14. Table 9.14. Associative Array Returned by posix_getgrnam() Entry Description name The name of the group gid The numeric group ID for the group number[n] The member list for the group members The number of members in the group posix_getgrgid() Syntax array posix_getgrgid(int gid); Description The posix_getgrgid() function returns an associative array with information about the group defined by the numeric gid (group ID). The associative array contains the entries listed in Table 9.15 . Table 9.15. Associative Array Returned by posix_getgrnam() Entry Description name The name of the GID's group gid The numeric group ID for the group PHP Developer’s Dictionary IT-SC book 381 number[n] The member list for the GID members The number of members in the GID posix_getpwnam() Syntax array posix_getpwnam(string name ); Description The posix_getpwnam() function returns an associative array with information about the username defined by name (see Table 9.16 ). This is the same information that is contained in the /etc/passwd file. Table 9.16. Associative Array Returned by posix_getpwnam() Entry Description name The username for the user passwd The encrypted password for the user uid The user ID for the user gid The group ID for the user gecos The real name for the user dir The user's home directory shell The user's preferred shell posix_getpwuid() Syntax array posix_getpwuid(int uid); Description The posix_getpwuid() function returns an associative array with information about the username defined by uid (see Table 9.17 ). This is the same information that is contained in the /etc/passwd file. Table 9.17. Associative Array Returned by posix_getpwnam() Entry Description name The username for the uid passwd The encrypted password for the uid uid The user ID for the uid PHP Developer’s Dictionary IT-SC book 382 gid The group ID for the uid gecos The real name for the uid dir The uid's home directory shell The uid's preferred shell posix_getrlimit() Syntax array posix_getrlimit(void); Description The posix_getrlimit() function returns an associative array about the resource limits of the operating system. The associative array returns the items listed in Table 9.18. Table 9.18. Associative Array Returned by posix_getrlimit() Number Description core Maximum core file size data Maximum data size stack Maximum stack size virtualmem Maximum virtual memory size totalmem Total system memory > rss Maximum resident set size maxproc Maximum number of processes memlock Maximum locked-in-memory address space cpu CPU time in seconds filesize Maximum file size openfiles Maximum number of open files Program Execution This section describes functions that allow external programs to return information to PHP. These functions differ in the way they return information to PHP, to the browser, or how they format the output. These are very powerful functions and allow PHP to employ any external executable that is available to the operating system. escapeshellcmd() Syntax string escapeshellcmd(string command); PHP Developer’s Dictionary IT-SC book 383 Description The escapeshellcmd() function escapes any characters in the string command . Escaping characters places backslashes in front of special characters before they are passed to the exec() or system() function. exec() Syntax string exec(string command, string [array], int [return_var]); Description The exec() function executes the given command and returns the last line from the result of the execution. The optional argument array will contain the entire output of the command. The optional argument return_val will return the actual return the status of the command. passthru() Syntax string passthru(string command, int [return_var]); Description The passthru() function executes the command and passes binary data, such as an image stream, directly back to the browser. The optional parameter return_var will return the status of the UNIX command. system() Syntax string system(string command, int [return_var]); Description PHP Developer’s Dictionary IT-SC book 384 The system() function executes the given command and returns the last line of the command's result. The optional parameter return_var will contain the result status of the command. Semaphore and Shared Memory This section describes the functions that are used to manage shared memory. Shared memory provides an efficient method of sharing memory between multiple processes. Because the data resides in the same physical RAM space and is accessible to multiple processes, a method must be devised to allow synchronous access to this memory. This method is achieved through the use of semaphores that provide synchronous access to shared memory segments by multiple processes and applications. This section assumes that you have a thorough understanding of semaphores and shared memory and the methods, processes, and techniques used to acquire semaphores and shared memory. sem_get() Syntax int sem_get(int key, int [ max_acquire ], int [ perm ]); Description The sem_get() function returns a semaphore ID that can be used to access semaphore defined by key . The optional parameter max_acquire is used to define the maximum number of processes that can acquire the semaphore at the same time. The optional parameter perm sets the permission bits for the semaphore. The default is 0666 , read/write. The function returns false, 0 , if an error occurred. Note Calling sem_get() a second time will return a different semaphore ID. However, both identifiers access the same semaphore. sem_acquire() Syntax int sem_acquire(int sem_identifier); . information to PHP. These functions differ in the way they return information to PHP, to the browser, or how they format the output. These are very powerful functions and allow PHP to employ. Description name The name of the GID's group gid The numeric group ID for the group PHP Developer’s Dictionary IT-SC book 381 number[n] The member list for the GID members . the uid passwd The encrypted password for the uid uid The user ID for the uid PHP Developer’s Dictionary IT-SC book 382 gid The group ID for the uid gecos The real