如何在AIX上安装gcc
默认情况下AIX是不带编译器，如果需要编译一些源代码，则可以安装linux上常用的gcc。AIX上支持安装linux的RPM包。首先要安装RPM包支持，下载地址为：
ftp://ftp.software.ibm.com/aix/freeSoftware/aixtoolbox/INSTALLP/ppc/rpm.rte
使用installp安装即可，如下表示已经安装
lslpp -l rpm.rte Fileset Level State Description ---------------------------------------------------------------------------- Path: /usr/lib/objrepos rpm.rte 3.0.5.40 COMMITTED RPM Package Manager Path: /etc/objrepos rpm.rte 3.0.5.40 COMMITTED RPM Package Manager
然后去下载gcc的安装包，进入下面的链接即可下载IBM提供的AIX Toolbox for Linux Applications，包括gcc：
http://www-03.ibm.com/systems/power/software/aix/linux/toolbox/download.html
AIX5.3上的gcc下载地址为：
ftp://ftp.software.ibm.com/aix/freeSoftware/aixtoolbox/RPMS/ppc/gcc/gcc-4.2.0-3.aix5.3.ppc.rpm
root>#rpm -i gcc-4.2.0-3.aix5.3.ppc.rpm root>#gcc -v Using built-in specs. Target: powerpc-ibm-aix5.3.0.0 Configured with: ../configure --with-as=/usr/bin/as --with-ld=/usr/bin/ld --enable-languages=c,c++,java --prefix=/opt/freeware --enable-threads --enable-version-specific-runtime-libs --host=powerpc-ibm-aix5.3.0.0 --target=powerpc-ibm-aix5.3.0.0 --build=powerpc-ibm-aix5.3.0.0 --disable-libjava-multilib Thread model: aix gcc version 4.2.0
在64位Linux上安装MemCached
在一台64位Linux的机器上安装了MemCached，遇到一个小问题，特记录之。
MemCached使用了libevent，所以必须先安装libevent。安装libevent到/usr/lib
wget http://www.monkey.org/~provos/libevent-1.4.9-stable.tar.gz gzip -d libevent-1.4.9-stable.tar.gz tar xvf libevent-1.4.9-stable.tar cd libevent-1.4.9-stable ./configure --prefix=/usr make make install
安装MemCached的到/u01/memcached
wget http://www.danga.com/memcached/dist/memcached-1.2.6.tar.gz gzip -d memcached-1.2.6.tar.gz tar xvf memcached-1.2.6.tar cd memcached-1.2.6 ./configure --prefix=/u01/memcached --with-libevent=/usr make make install
但是执行memcached命令时出现错误：
#/u01/memcached/bin/memcached -h /u01/memcached/bin/memcached: error while loading shared libraries: libevent-1.4.so.2: cannot open shared object file: No such file or directory
一般对于这种依赖的库找不到的情况，在Linux中可以通过设置LD_DEBUG环境变量来获得更多的信息
#LD_DEBUG=help ls Valid options for the LD_DEBUG environment variable are: libs display library search paths reloc display relocation processing files display progress for input file symbols display symbol table processing bindings display information about symbol binding versions display version dependencies all all previous options combined statistics display relocation statistics unused determined unused DSOs help display this help message and exit To direct the debugging output into a file instead of standard output a filename can be specified using the LD_DEBUG_OUTPUT environment variable.
这里由于是库文件依赖有问题，则使用libs参数：
#LD_DEBUG=libs /u01/memcached/bin/memcached -h
30596: find library=libevent-1.4.so.2 [0]; searching
30596: search cache=/etc/ld.so.cache
30596: search path=/lib64/tls/x86_64:/lib64/tls:/lib64/x86_64:/lib64:/usr/lib64/tls/x86_64
/usr/lib64/tls:/usr/lib64/x86_64:/usr/lib64
(system search path)
30596: trying file=/lib64/tls/x86_64/libevent-1.4.so.2
30596: trying file=/lib64/tls/libevent-1.4.so.2
30596: trying file=/lib64/x86_64/libevent-1.4.so.2
30596: trying file=/lib64/libevent-1.4.so.2
30596: trying file=/usr/lib64/tls/x86_64/libevent-1.4.so.2
30596: trying file=/usr/lib64/tls/libevent-1.4.so.2
30596: trying file=/usr/lib64/x86_64/libevent-1.4.so.2
30596: trying file=/usr/lib64/libevent-1.4.so.2
30596:
/u01/memcached/bin/memcached: error while loading shared libraries: libevent-1.4.so.2:
cannot open shared object file: No such file or directory
可以看到是在加载/usr/lib64/libevent-1.4.so.2文件时出现了问题，系统中确实是没有该文件的，查找后发现libevent-1.4.so.2存在于/usr/lib目录，这可能是libevent在64位Linux系统上的一个bug吧，没有关系，复制一份或者建一个软链接即可解决问题。
#ln -s /usr/lib/libevent-1.4.so.2 /usr/lib64/libevent-1.4.so.2 #/u01/memcached/bin/memcached -h memcached 1.2.6 -pTCP port number to listen on (default: 11211) -U UDP port number to listen on (default: 0, off) -s unix socket path to listen on (disables network support) -a access mask for unix socket, in octal (default 0700) -l interface to listen on, default is INDRR_ANY -d run as a daemon -r maximize core file limit -u assume identity of (only when run as root) -m max memory to use for items in megabytes, default is 64 MB -M return error on memory exhausted (rather than removing items) -c max simultaneous connections, default is 1024 -k lock down all paged memory. Note that there is a limit on how much memory you may lock. Trying to allocate more than that would fail, so be sure you set the limit correctly for the user you started the daemon with (not for -u user; under sh this is done with 'ulimit -S -l NUM_KB'). -v verbose (print errors/warnings while in event loop) -vv very verbose (also print client commands/reponses) -h print this help and exit -i print memcached and libevent license -b run a managed instanced (mnemonic: buckets) -P save PID in , only used with -d option -f chunk size growth factor, default 1.25 -n minimum space allocated for key+value+flags, default 48
启动MemCached，-m表示分配的内存
#/u01/memcached/bin/memcached -d -m 1024 -u admin -l 127.0.0.1 -p 11211
Linux中如何让进程在后台运行
在Linux中，如果要让进程在后台运行，一般情况下，我们在命令后面加上&即可，实际上，这样是将命令放入到一个作业队列中了：
$ ./test.sh & [1] 17208 $ jobs -l [1]+ 17208 Running ./test.sh &
对于已经在前台执行的命令，也可以重新放到后台执行，首先按ctrl+z暂停已经运行的进程，然后使用bg命令将停止的作业放到后台运行：
$ ./test.sh [1]+ Stopped ./test.sh $ bg %1 [1]+ ./test.sh & $ jobs -l [1]+ 22794 Running ./test.sh &
卸载rpm包遭遇error: specifies multiple packages
准备在Redhat Linux系统上安装MySQL5.1，先卸载自带的低版本MySQL，结果不知怎么搞的，同一个package出现了两次，版本也都是一样的：
mysqlclient10-3.23.58-4.RHEL4.1
mysql-4.1.20-2.RHEL4.1
mysql-4.1.20-2.RHEL4.1
mysqlclient10-3.23.58-4.RHEL4.1
尝试卸载：
error: "mysqlclient10-3.23.58-4.RHEL4.1" specifies multiple packages
通过man rpm，发现–allmatches应该可以解决这个问题：
–allmatches
Remove all versions of the package which match PACKAGE_NAME. Normally an error is issued if PACKAGE_NAME matches
multiple packages.
rpm -e --allmatches mysql-4.1.20-2.RHEL4.1
warning: /etc/my.cnf saved as /etc/my.cnf.rpmsave
ok，系统自带的旧版本MySQL卸载完成。
