exec函数簇

exec一共有六种函数，都是以exec开头。

int execl(const char *path, const char *arg, ...);
int execlp(const char *file, const char *arg, ...);
int execle(const char *path, const char *arg, ..., char * const envp[]);
int execv(const char *path, char *const argv[]);
int execvp(const char *file, char *const argv[]);
int execve(const char *path, char *const argv[], char *const envp[]);

后缀	含义
l	l代表list,接受以逗号的参数，最后是以(char *)0结束。
v	v代表vector,接受参数数组，数组以NULL结束。
p	p代表取用PATH环境环境寻找可执行文件，不需要单独传入一个路径参数。
e	取代当前的环境环境

主程序

#include <stdio.h>
#include <unistd.h>
#include <sys/wait.h>
#include <errno.h>
extern char **environ;
int main(){
    char *env[]={"USER=hh","PATH=/home/map/users",NULL};
    int pid;
    if((pid=fork())<0){
        perror("fork error;");
    }else if(pid==0){
        execle("/home/map/users/maxin/cpp/chr08/test","test","hello","world",(char *)0,env);
        perror("exec error:");
    }
    if(waitpid(pid,NULL,0)!=pid){
        perror("wait error");
    }
    printf("----------------------------------------
");
    if((pid=fork())<0){
        perror("fork error;");
    }else if(pid==0){
        execle("/home/map/users/maxin/cpp/chr08/test","test","hello","world",(char *)0,environ);
        perror("exec error:");
    }
    if(waitpid(pid,NULL,0)!=pid){
        perror("wait error");
    }

    printf("----------------------------------------
");
    if((pid=fork())<0){
        perror("fork error;");
    }else if(pid==0){
        execlp("./test","./test","hello",(char *)0);
        perror("exec error:");
    }
    if(waitpid(pid,NULL,0)!=pid){
        perror("wait error");
    }
}

被调用的程序

#include <stdio.h>
#include <stdlib.h>
extern char **environ;
void showEnv();
int main(int args,const char *argv[]){
    printf("args%d
",args );
    for(int i=0;i!=args;++i){
        printf("argv[%d]:%s
",i,argv[i]);
    }
    printf("USER:%s
", getenv("USER"));
    printf("PATH:%s
", getenv("PATH"));
    showEnv();
}
void showEnv(){
    int i=0;
    while(environ[i]){
        printf("environ[%d]:%s
",i,environ[i] );
        ++i;
    }
    printf("----------------------END---------------------------
" );
}

 最后的显示结果

args3
argv[0]:test
argv[1]:hello
argv[2]:world
USER:hh
PATH:/home/map/users
environ[0]:USER=hh
environ[1]:PATH=/home/map/users
----------------------END---------------------------
----------------------------------------
args3
argv[0]:test
argv[1]:hello
argv[2]:world
USER:map
PATH:/home/tools/tools/svn/1.6.5/64/bin:/home/tools/tools/scmtools/usr/bin:/home/tools/tools/../bin/64/:/home/tools/tools/maven/apache-maven-2.2.0/bin:/home/tools/tools/ant/apache-ant-1.6.5/bin:/home/tools/tools/ant/apache-ant-1.7.1/bin:/home/tools/tools/php/5.2.17/64/bin:/java/jdk1.6.0_06/bin:/java/jdk1.6.0_06/jre/bin:/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/usr/X11R6/bin:/usr/share/*****/bin:/opt/bin:/home/opt/bin:/home/map/bin:/home/work/.nlpcloud/nlpc/bin:/home/work/.qu/qu:/home/map/bin:/home/map/users/yinsongyang/fis/node-v0.10.26-linux-x64/bin:/home/map/users/yinsongyang/fis/jre1.7.0_55/bin:/home/map/odp24/php/bin
environ[0]:MAC=64
environ[1]:MANPATH=:/tools/*****_manpage/man
environ[2]:HOSTNAME=cq01-rdqa-*****.*****.*****.com
environ[3]:TERM=vt100
environ[4]:SHELL=/bin/bash
environ[5]:HISTSIZE=1000
environ[6]:SSH_CLIENT=172.22.4.13 36038 22
environ[7]:OLDPWD=/home/map/users/maxin/cpp
environ[8]:MAVEN_2_2_1=/home/tools/tools/maven/apache-maven-2.2.1/bin
environ[9]:SSH_TTY=/dev/pts/2
environ[10]:MAVEN_3_0_4=/home/tools/tools/maven/apache-maven-3.0.4/bin
environ[11]:ANT_HOME=/home/tools/tools/ant/apache-ant-1.6.5
environ[12]:USER=map
environ[13]:LS_COLORS=no=00:fi=00:di=01;34:ln=01;36:pi=40;33:so=01;35:bd=40;33;01:cd=40;33;01:or=01;05;37;41:mi=01;05;37;41:ex=01;32:*.cmd=01;32:*.exe=01;32:*.com=01;32:*.btm=01;32:*.bat=01;32:*.sh=01;32:*.csh=01;32:*.tar=01;31:*.tgz=01;31:*.arj=01;31:*.taz=01;31:*.lzh=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.gz=01;31:*.bz2=01;31:*.bz=01;31:*.tz=01;31:*.rpm=01;31:*.cpio=01;31:*.jpg=01;35:*.gif=01;35:*.bmp=01;35:*.xbm=01;35:*.xpm=01;35:*.png=01;35:*.tif=01;35:
environ[14]:MAIL=/var/spool/mail/map
environ[15]:PATH=/home/tools/tools/svn/1.6.5/64/bin:/home/tools/tools/scmtools/usr/bin:/home/tools/tools/../bin/64/:/home/tools/tools/maven/apache-maven-2.2.0/bin:/home/tools/tools/ant/apache-ant-1.6.5/bin:/home/tools/tools/ant/apache-ant-1.7.1/bin:/home/tools/tools/php/5.2.17/64/bin:/java/jdk1.6.0_06/bin:/java/jdk1.6.0_06/jre/bin:/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/usr/X11R6/bin:/usr/share/*****/bin:/opt/bin:/home/opt/bin:/home/map/bin:/home/work/.nlpcloud/nlpc/bin:/home/work/.qu/qu:/home/map/bin:/home/map/users/yinsongyang/fis/node-v0.10.26-linux-x64/bin:/home/map/users/yinsongyang/fis/jre1.7.0_55/bin:/home/map/odp24/php/bin
environ[16]:INPUTRC=/etc/inputrc
environ[17]:PWD=/home/map/users/maxin/cpp/chr08
environ[18]:JAVA_HOME=/java/jdk1.6.0_06
environ[19]:LANG=en_US
environ[20]:JAVA_HOME_1_6=/home/tools/tools/java/jdk1.6.0_20
environ[21]:JAVA_HOME_1_5=/home/tools/tools/java/jdk1.5.0_07
environ[22]:ANT_HOME_1_7=/home/tools/tools/ant/apache-ant-1.7.1
environ[23]:SHLVL=1
environ[24]:HOME=/home/map
environ[25]:LOGNAME=map
environ[26]:CLASSPATH=:/java/jdk1.6.0_06/lib:/java/jdk1.6.0_06/jre/lib
environ[27]:SSH_CONNECTION=172.22.4.13 36038 10.48.52.44 22
environ[28]:PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:
environ[29]:LESSOPEN=|/usr/bin/lesspipe.sh %s
environ[30]:G_BROKEN_FILENAMES=1
environ[31]:_=./a.out
----------------------END---------------------------
----------------------------------------
args2
argv[0]:./test
argv[1]:hello
USER:map
PATH:/home/tools/tools/svn/1.6.5/64/bin:/home/tools/tools/scmtools/usr/bin:/home/tools/tools/../bin/64/:/home/tools/tools/maven/apache-maven-2.2.0/bin:/home/tools/tools/ant/apache-ant-1.6.5/bin:/home/tools/tools/ant/apache-ant-1.7.1/bin:/home/tools/tools/php/5.2.17/64/bin:/java/jdk1.6.0_06/bin:/java/jdk1.6.0_06/jre/bin:/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/usr/X11R6/bin:/usr/share/*****/bin:/opt/bin:/home/opt/bin:/home/map/bin:/home/work/.nlpcloud/nlpc/bin:/home/work/.qu/qu:/home/map/bin:/home/map/users/yinsongyang/fis/node-v0.10.26-linux-x64/bin:/home/map/users/yinsongyang/fis/jre1.7.0_55/bin:/home/map/odp24/php/bin
environ[0]:MAC=64
environ[1]:MANPATH=:/tools/*****_manpage/man
environ[2]:HOSTNAME=cq01-rdqa-*****.*****.*****.com
environ[3]:TERM=vt100
environ[4]:SHELL=/bin/bash
environ[5]:HISTSIZE=1000
environ[6]:SSH_CLIENT=172.22.4.13 36038 22
environ[7]:OLDPWD=/home/map/users/maxin/cpp
environ[8]:MAVEN_2_2_1=/home/tools/tools/maven/apache-maven-2.2.1/bin
environ[9]:SSH_TTY=/dev/pts/2
environ[10]:MAVEN_3_0_4=/home/tools/tools/maven/apache-maven-3.0.4/bin
environ[11]:ANT_HOME=/home/tools/tools/ant/apache-ant-1.6.5
environ[12]:USER=map
environ[13]:LS_COLORS=no=00:fi=00:di=01;34:ln=01;36:pi=40;33:so=01;35:bd=40;33;01:cd=40;33;01:or=01;05;37;41:mi=01;05;37;41:ex=01;32:*.cmd=01;32:*.exe=01;32:*.com=01;32:*.btm=01;32:*.bat=01;32:*.sh=01;32:*.csh=01;32:*.tar=01;31:*.tgz=01;31:*.arj=01;31:*.taz=01;31:*.lzh=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.gz=01;31:*.bz2=01;31:*.bz=01;31:*.tz=01;31:*.rpm=01;31:*.cpio=01;31:*.jpg=01;35:*.gif=01;35:*.bmp=01;35:*.xbm=01;35:*.xpm=01;35:*.png=01;35:*.tif=01;35:
environ[14]:MAIL=/var/spool/mail/map
environ[15]:PATH=/home/tools/tools/svn/1.6.5/64/bin:/home/tools/tools/scmtools/usr/bin:/home/tools/tools/../bin/64/:/home/tools/tools/maven/apache-maven-2.2.0/bin:/home/tools/tools/ant/apache-ant-1.6.5/bin:/home/tools/tools/ant/apache-ant-1.7.1/bin:/home/tools/tools/php/5.2.17/64/bin:/java/jdk1.6.0_06/bin:/java/jdk1.6.0_06/jre/bin:/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/usr/X11R6/bin:/usr/share/*****/bin:/opt/bin:/home/opt/bin:/home/map/bin:/home/work/.nlpcloud/nlpc/bin:/home/work/.qu/qu:/home/map/bin:/home/map/users/yinsongyang/fis/node-v0.10.26-linux-x64/bin:/home/map/users/yinsongyang/fis/jre1.7.0_55/bin:/home/map/odp24/php/bin
environ[16]:INPUTRC=/etc/inputrc
environ[17]:PWD=/home/map/users/maxin/cpp/chr08
environ[18]:JAVA_HOME=/java/jdk1.6.0_06
environ[19]:LANG=en_US
environ[20]:JAVA_HOME_1_6=/home/tools/tools/java/jdk1.6.0_20
environ[21]:JAVA_HOME_1_5=/home/tools/tools/java/jdk1.5.0_07
environ[22]:ANT_HOME_1_7=/home/tools/tools/ant/apache-ant-1.7.1
environ[23]:SHLVL=1
environ[24]:HOME=/home/map
environ[25]:LOGNAME=map
environ[26]:CLASSPATH=:/java/jdk1.6.0_06/lib:/java/jdk1.6.0_06/jre/lib
environ[27]:SSH_CONNECTION=172.22.4.13 36038 10.48.52.44 22
environ[28]:PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:
environ[29]:LESSOPEN=|/usr/bin/lesspipe.sh %s
environ[30]:G_BROKEN_FILENAMES=1
environ[31]:_=./a.out
----------------------END---------------------------