靈活使用getconf命令來獲取系統資訊

工程師WWW發表於2016-04-08
我們時常需要查詢系統相關的資訊，比如頁面大小，整數大小之類，如果編寫程式去計算會比較繁瑣，這裡有一個很有用的命令，可以用來獲取系統相關資訊。它就是getconf。

$ getconf PAGE_SIZE
4096
$ getconf INT_MAX
2147483647

可以取得的相關資訊如下(參考相關資料，在又在版本上會有些不同）：
_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

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