灵活使用getconf命令来获取系统信息

我们时常需要查询系统相关的信息，比如页面大小，整数大小之类，如果编写程序去计算会比较繁琐，这里有一个很有用的命令，可以用来获取系统相关信息。它就是getconf。

getconf 用途将系统配置变量值写入标准输出,比如：

getconf PAGE_SIZE 查看系统内存分页大小

getconf LONG_BIT 看linux是32位还是64位最简单的方法

getconf -a 查看全部系统变量

$ getconf PAGE_SIZE

4096

$ getconf INT_MAX

2147483647

$ getconf LONG_BIT

64

可以取得的相关信息如下(参考相关资料，在又在版本上会有些不同）：

_CS_PATH	Value for the PATH environment variable used to find commands.
ARG_MAX	Maximum length, in bytes, of the arguments for one of the exec subroutines, including environment data.
BC_BASE_MAX	Maximum value allowed for the obase variable with the bc command.
BC_DIM_MAX	Maximum number of elements permitted in an array by the bc command.
BC_SCALE_MAX	Maximum value allowed for the scale variable with the bc command.
BC_STRING_MAX	Maximum length of a string constant accepted by the bc command.
CHARCLASS_NAME_MAX	Maximum number of bytes in a character class name.
CHAR_BIT	Number of bits in a type character.
CHAR_MAX	Maximum value of a type character.
CHAR_MIN	Minimum value of a type character.
CHILD_MAX	Maximum number of simultaneous processes for each real user ID.
CLK_TCK	Number of clock ticks per second returned by the time subroutine.
COLL_WEIGHTS_MAX	Maximum number of weights that can be assigned to an entry in the LC_COLLATE locale stanza in a locale-definition file.
CS_PATH	Value of the PATH environment variable used to find commands.
EXPR_NEST_MAX	Maximum number of expressions that can be nested within parentheses by the expr command.
INT_MAX	Maximum value of a type int.
INT_MIN	Minimum value of a type int.
LINE_MAX	Maximum length, in bytes, of a command's input line (either standard input or another file) when the utility is described as processing text files. The length includes room for the trailing new-line character.
LONG_BIT	Number of bits in a type long int.
LONG_MAX	Maximum value of a type long int.
LONG_MIN	Minimum value of a type long int.
MB_LEN_MAX	Maximum number of bytes in a character for any supported locale.
NGROUPS_MAX	Maximum number of simultaneous supplementary group IDs for each process.
NL_ARGMAX	Maximum value of digit in calls to the printf and scanf subroutines.
NL_LANGMAX	Maximum number of bytes in a LANG name.
NL_MSGMAX	Maximum message number.
NL_NMAX	Maximum number of bytes in an N-to-1 collation mapping.
NL_SETMAX	Maximum set number.
NL_TEXTMAX	Maximum number of bytes in a message string.
NZERO	Default process priority.
OPEN_MAX	Maximum number of files that one process can have open at one time.
PATH	Sequence of colon-separated path prefixes used to find commands.
RE_DUP_MAX	Maximum number of repeated occurrences of a regular expression permitted when using the interval-notation parameters, such as the m and n parameters with the ed command.
SCHAR_MAX	Maximum value of a type signed char.
SCHAR_MIN	Minimum value of a type signed char.
SHRT_MAX	Maximum value of a type short.
SHRT_MIN	Minimum value of a type short.
SSIZE_MAX	Maximum value of an object of type ssize_t.
STREAM_MAX	Number of streams that one process can have open at one time.
TMP_MAX	Minimum number of unique path names generated by the tmpnam subroutine. Maximum number of times an application can reliably call the tmpnam subroutine.
TZNAME_MAX	Maximum number of bytes supported for the name of a time zone (not the length of the TZ environment variable).
UCHAR_MAX	Maximum value of a type unsigned char.
UINT_MAX	Maximum value of a type unsigned int.
ULONG_MAX	Maximum value of a type unsigned long int.
USHRT_MAX	Maximum value of a type unsigned short int.
WORD_BIT	Number of bits in a word or type int