{"id":5902,"date":"2009-12-30T15:51:40","date_gmt":"2009-12-30T10:21:40","guid":{"rendered":"http:\/\/froisa.com\/?p=188"},"modified":"2009-12-30T15:51:40","modified_gmt":"2009-12-30T10:21:40","slug":"free-m-2","status":"publish","type":"post","link":"https:\/\/www.trueangle.org\/index.php\/2009\/12\/30\/free-m-2\/","title":{"rendered":"free – Display amount of free and used memory in the system"},"content":{"rendered":"

A UNIX Command<\/u><\/h4>\n
\n$free\n             total       used       free     shared    buffers     cached\nMem:        507008     432908      74100          0      14700     186816\n-\/+ buffers\/cache:     231392     275616\nSwap:      1485972          0    1485972\n$free -m\n             total       used       free     shared    buffers     cached\nMem:           495        422         72          0         14        182\n-\/+ buffers\/cache:        225        269\nSwap:         1451          0       1451\n$\n\n<\/pre>\n
 UNIX Explanation <\/u><\/h4>\n
\nDisplay amount of free and used memory in the system.\n<\/pre>\n
<\/p>\n
 Related Source Code Exposition <\/u><\/h4>\n

\n#define S(X) ( ((unsigned long long)(X) <> shift)<\/p>\n
const char help_message[] =
\n\"usage: free [-b|-k|-m|-g] [-l] [-o] [-t] [-s delay] [-c count] [-V]\\n\"
\n\"  -b,-k,-m,-g show output in bytes, KB, MB, or GB\\n\"
\n\"  -l show detailed low and high memory statistics\\n\"
\n\"  -o use old format (no -\/+buffers\/cache line)\\n\"
\n\"  -t display total for RAM + swap\\n\"
\n\"  -s update every [delay] seconds\\n\"
\n\"  -c update [count] times\\n\"
\n\"  -V display version information and exit\\n\"
\n;<\/p>\n
int main(int argc, char *argv[]){
\n    int i;
\n    int count = 0;
\n    int shift = 10;
\n    int pause_length = 0;
\n    int show_high = 0;
\n    int show_total = 0;
\n    int old_fmt = 0;<\/p>\n
    \/* check startup flags *\/
\n    while( (i = getopt(argc, argv, \"bkmglotc:s:V\") ) != -1 )
\n        switch (i) {
\n        case 'b': shift = 0;  break;
\n        case 'k': shift = 10; break;
\n        case 'm': shift = 20; break;
\n        case 'g': shift = 30; break;
\n        case 'l': show_high = 1; break;
\n        case 'o': old_fmt = 1; break;
\n        case 't': show_total = 1; break;
\n        case 's': pause_length = 1000000 * atof(optarg); break;
\n        case 'c': count = strtoul(optarg, NULL, 10); break;
\n\tcase 'V': display_version(); exit(0);
\n        default:
\n            fwrite(help_message,1,strlen(help_message),stderr);
\n\t    return 1;
\n    }<\/p>\n
    do {
\n        meminfo();
\n        printf(\"             total       used       free     shared    buffers     cached\\n\");
\n        printf(
\n            \"%-7s %10Lu %10Lu %10Lu %10Lu %10Lu %10Lu\\n\", \"Mem:\",
\n            S(kb_main_total),
\n            S(kb_main_used),
\n            S(kb_main_free),
\n            S(kb_main_shared),
\n            S(kb_main_buffers),
\n            S(kb_main_cached)
\n        );
\n        \/\/ Print low vs. high information, if the user requested it.
\n        \/\/ Note we check if low_total==0: if so, then this kernel does
\n        \/\/ not export the low and high stats.  Note we still want to
\n        \/\/ print the high info, even if it is zero.
\n        if (show_high) {
\n            printf(
\n                \"%-7s %10Lu %10Lu %10Lu\\n\", \"Low:\",
\n                S(kb_low_total),
\n                S(kb_low_total - kb_low_free),
\n                S(kb_low_free)
\n            );
\n            printf(
\n                \"%-7s %10Lu %10Lu %10Lu\\n\", \"High:\",
\n                S(kb_high_total),
\n                S(kb_high_total - kb_high_free),
\n                S(kb_high_free)
\n            );
\n        }
\n        if(!old_fmt){
\n            unsigned KLONG buffers_plus_cached = kb_main_buffers + kb_main_cached;
\n            printf(
\n                \"-\/+ buffers\/cache: %10Lu %10Lu\\n\",
\n                S(kb_main_used - buffers_plus_cached),
\n                S(kb_main_free + buffers_plus_cached)
\n            );
\n        }
\n        printf(
\n            \"%-7s %10Lu %10Lu %10Lu\\n\", \"Swap:\",
\n            S(kb_swap_total),
\n            S(kb_swap_used),
\n            S(kb_swap_free)
\n        );
\n        if(show_total){
\n            printf(
\n                \"%-7s %10Lu %10Lu %10Lu\\n\", \"Total:\",
\n                S(kb_main_total + kb_swap_total),
\n                S(kb_main_used  + kb_swap_used),
\n                S(kb_main_free  + kb_swap_free)
\n            );
\n        }
\n        if(pause_length){
\n\t    fputc('\\n', stdout);
\n\t    fflush(stdout);
\n\t    if (count != 1) usleep(pause_length);
\n\t}
\n    } while(pause_length && --count);<\/p>\n
    return 0;
\n}
\n<\/code>
\n<\/p>\n
 Source Code Highlight<\/u><\/h4>\n

\n#define S(X) ( ((unsigned long long)(X) <> shift)
\n<\/code><\/p>\n
\nit  takes  a  number,  X,  casts  it  to  a  'long  long'\n(presumably the  longest int type  on your system  ?) and\nthen it left-shifts by  10 (meaning, the the positions of\nall bits are shifted 10 places to the left) only to shift\nit back right 'shift' number of positions.\n\nsource : nickname - psuedonymous. server - irc.freenode.net\n<\/pre>\n
<\/p>\n
 Featured Image<\/u><\/h4>\n
\"\"<\/a>
\n<\/p>\n
 Related Knowledge <\/u><\/h4>\n
\nfree displays the total  amount of free and used physical\nand swap  memory in  the system, as  well as  the buffers\nused by  the kernel.  The shared memory  column should be\nignored; it is obsolete.\n\nsource : debian manual for free.\n\n<\/pre>\n","protected":false},"excerpt":{"rendered":"
A UNIX Command $free total used free shared buffers cached Mem: 507008 432908 74100 0 14700 186816 -\/+ buffers\/cache: 231392 275616 Swap: 1485972 0 1485972 $free -m total used free shared buffers cached Mem: 495 422 72 0 14 182 -\/+ buffers\/cache: 225 269 Swap: 1451 0 1451 $ UNIX Explanation Display amount of free … <\/p>\n
Continue reading “free – Display amount of free and used memory in the system”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":-1,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[83],"tags":[792,1108],"_links":{"self":[{"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/posts\/5902"}],"collection":[{"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/comments?post=5902"}],"version-history":[{"count":0,"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/posts\/5902\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/"}],"wp:attachment":[{"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/media?parent=5902"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/categories?post=5902"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.trueangle.org\/index.php\/wp-json\/wp\/v2\/tags?post=5902"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}