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    <p>The (Linux-specific) system call <code>sysinfo(struct sysinfo* info)</code> fills in <code>info</code> with the following:</p> <pre><code>struct sysinfo { long uptime; /* Seconds since boot */ unsigned long loads[3]; /* 1, 5, and 15 minute load averages */ unsigned long totalram; /* Total usable main memory size */ unsigned long freeram; /* Available memory size */ unsigned long sharedram; /* Amount of shared memory */ unsigned long bufferram; /* Memory used by buffers */ unsigned long totalswap; /* Total swap space size */ unsigned long freeswap; /* swap space still available */ unsigned short procs; /* Number of current processes */ unsigned long totalhigh; /* Total high memory size */ unsigned long freehigh; /* Available high memory size */ unsigned int mem_unit; /* Memory unit size in bytes */ char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding for libc5 */ }; </code></pre> <p>Of which <code>totalswap</code> and <code>freeswap</code> might be what you are after.</p> <p>I don't know how you do native platform invocation in Java, but this is a good alternative to parsing the <code>/proc/swaps</code> file yourself.</p> <h1>EDIT:</h1> <p>I played a bit with <a href="http://www.github.com/twall/jna" rel="nofollow">JNA</a> and came up with this:</p> <pre><code>import com.sun.jna.Library; import com.sun.jna.Native; import com.sun.jna.Structure; import com.sun.jna.NativeLong; public class Test { public interface CStdLib extends Library { static class SysInfo extends Structure { public NativeLong uptime; public NativeLong[] loads = new NativeLong[3]; public NativeLong totalram; public NativeLong freeram; public NativeLong sharedram; public NativeLong bufferram; public NativeLong totalswap; public NativeLong freeswap; public short procs; public NativeLong totalhigh; public NativeLong freehigh; public int mem_unit; /* some padding? */ } int sysinfo(SysInfo info); } public static void main(String[] args) { CStdLib c = (CStdLib)Native.loadLibrary("c", CStdLib.class); CStdLib.SysInfo s = new CStdLib.SysInfo(); c.sysinfo(s); System.out.println("totalram: " + s.totalram); } } </code></pre> <p>Unfortunately you're going to have issues where the value is too large for a signed <code>long</code> and thus you might get the wrong value in Java, which I am seeing when trying to read the swap values on my machine.</p> <p>Hope this helps! (Caveat: I have never been confused with a Java programmer <code>:)</code> )</p>
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    1. POHow to get swap size in Linux from /proc/swaps?
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    1. USJohn Ledbetter
    1. USJohn Ledbetter
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    1. COVery good answer! Unfortunately I'm new to Java and I don't know to write the code in Java. Maybe I can use JNI.
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    2. COIs there other useful system call for monitoring Linux performance? For example number of total network sessions?
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    3. COThank you but I use Linux.
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