我使用过的Linux命令之source - 在当前shell环境中执行指定文件中的命令

本文链接：http://codingstandards.iteye.com/blog/837935 ? （转载请注明出处）

用途说明

source命令是bash中的内建命令，它等同于点命令（.），用于读取和在当前shell环境中执行指定文件中的命令，执行完毕之后退出码为该文件中的最后一个命令的退出码（Read? and? execute commands from filename in the current shell environment and return the exit status of the last command executed from filename.）。指定的文件可以没有执行权限。

在当前shell中执行和在子shell中执行的区别是，后者定义的变量和函数在执行结束后就消失了，而前者却可以保留下来。有时候我们修改了/etc/profile里面的内容，如增加了环境变量，那么要立即生效的话，就必须使用source命令或者点命令在当前shell中执行一下。

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常用参数

格式： .? filename [arguments]
格式： source filename [arguments]

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在后面的示例中会分别对各种情况举例演示。

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使用示例

示例一

[root@web imx_web3q]# help source
source: source filename [arguments]
??? Read and execute commands from FILENAME and return.? The pathnames
??? in $PATH are used to find the directory containing FILENAME.? If any
??? ARGUMENTS are supplied, they become the positional parameters when
??? FILENAME is executed.
[root@web imx_web3q]#

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示例二 修改/etc/profile之后使之立即生效

[root@web imx_web3q]# vi /etc/profile

[root@web imx_web3q]# . /etc/profile
[root@web imx_web3q]#

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示例三 在PATH中搜索命令

man source中说道：如果filename不包含斜杠（/），那么从PATH环境变量指定的那些路径搜索filename，这个文件不必是可执行 的。（If filename does not contain a slash, file names in? PATH? are used? to? find the directory containing filename.? The file searched for in PATH need not be executable.）如果在PATH中找不到指定文件，当bash不是posix模式时，将在当前目录下搜索该文件。（When bash is not in posix mode, the current directory is searched if no file is found in PATH.）如果shopt里的sourcepath关闭，则不在PATH中搜索指定文件。（If? the sourcepath? option? to? the shopt builtin command is turned off, the PATH is not searched.）

[root@new55 ~]# shopt

cdable_vars???? off
cdspell???????? off
checkhash?????? off
checkwinsize??? on
cmdhist???????? on
dotglob???????? off
execfail??????? off
expand_aliases? on
extdebug??????? off
extglob???????? on
extquote??????? on
failglob??????? off
force_fignore?? on
gnu_errfmt????? off
histappend????? off
histreedit????? off
histverify????? off
hostcomplete??? off
huponexit?????? off
interactive_comments??? on
lithist???????? off
login_shell???? on
mailwarn??????? off
no_empty_cmd_completion off
nocaseglob????? off
nocasematch???? off
nullglob??????? off
progcomp??????? on
promptvars????? on
restricted_shell??????? off
shift_verbose?? off
sourcepath????? on
xpg_echo??????? off
[root@new55 ~]# echo $PATH
/usr/kerberos/sbin:/usr/kerberos/bin:/opt/apache/apache-ant-1.8.1/bin:/usr/java/jdk1.6.0_21/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin :/root/bin
[root@new55 ~]# ls -l /usr/bin/sj.sh
-rwxr-xr-x 1 root root 453 09-15 04:46 /usr/bin/sj.sh

[root@new55 ~]# cat /usr/bin/sj.sh
#!/bin/sh

listpids()
{
??????? #ps -ef|grep java|grep -v grep
??????? COLUMNS=1024 ps h -C java -f
}

showpids()
{
??????? while read u p pp t1 t2 tty cpu cmd;
??????? do
??????????????? ls -l /proc/$p/cwd
??????????????? echo $p $cwd $cmd
??????????????? echo
??????? done
}

showpidof()
{
??????? while read u p pp t1 t2 tty cpu cmd;
??????? do
??????????????? if ls -l /proc/$p/cwd | grep -q $1; then
??????????????????????? echo $p
??????????????? elif echo $cmd | grep -q $1; then