在PHP中使用shell_exec geogig-init时权限被拒绝

GeoGig是一个新的地理数据版本控制工具，它具有与git相同的功能。我正在实现这个新工具，但在使用shell_exec（"geogig-init"）时遇到了一个问题。我在apache中设置了PATH变量，它指向/opt/geogig/bin，其中是geogig的二进制文件，有了它，我可以在php中使用命令行geogig。我的问题是，这个命令创建了本地存储库的某个部分，但得到了shell_exec抛出的错误：

12:15:33.678 [main] ERROR o.locationtech.geogig.cli.GeogigCLI - An unhandled error occurred: java.io.IOException: Permission denied. See the log for more details.
org.locationtech.geogig.storage.ConfigException: java.io.IOException: Permission denied
    at org.locationtech.geogig.storage.fs.IniFileConfigDatabase$2.iniFile(IniFileConfigDatabase.java:63) ~[geogig-core-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.storage.fs.INIFile.checkReload(INIFile.java:330) ~[geogig-core-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.storage.fs.INIFile.get(INIFile.java:56) ~[geogig-core-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.storage.fs.IniFileConfigDatabase.getGlobal(IniFileConfigDatabase.java:100) ~[geogig-core-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.storage.bdbje.JEObjectDatabase.newTransaction(JEObjectDatabase.java:878) ~[geogig-bdbje-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.storage.bdbje.JEObjectDatabase.putInternal(JEObjectDatabase.java:630) ~[geogig-bdbje-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.storage.AbstractObjectStore.put(AbstractObjectStore.java:224) ~[geogig-core-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.storage.ForwardingObjectDatabase.put(ForwardingObjectDatabase.java:127) ~[geogig-core-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.di.ObjectDatabasePutInterceptor$GraphUpdatingObjectDatabase.put(ObjectDatabasePutInterceptor.java:65) ~[geogig-core-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.storage.ForwardingObjectDatabase.put(ForwardingObjectDatabase.java:127) ~[geogig-core-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.api.porcelain.InitOp.callInternal(InitOp.java:216) ~[geogig-core-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.api.porcelain.InitOp._call(InitOp.java:125) ~[geogig-core-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.api.porcelain.InitOp._call(InitOp.java:64) ~[geogig-core-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.api.AbstractGeoGigOp.call(AbstractGeoGigOp.java:133) ~[geogig-core-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.cli.porcelain.Init.runInternal(Init.java:99) ~[geogig-cli-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.cli.AbstractCommand.run(AbstractCommand.java:68) ~[geogig-cli-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.cli.GeogigCLI.executeInternal(GeogigCLI.java:543) [geogig-cli-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.cli.GeogigCLI.execute(GeogigCLI.java:385) [geogig-cli-1.0-RC1a.jar:1.0-RC1a]
    at org.locationtech.geogig.cli.GeogigCLI.main(GeogigCLI.java:340) [geogig-cli-1.0-RC1a.jar:1.0-RC1a]
Caused by: java.io.IOException: Permission denied
    at java.io.UnixFileSystem.createFileExclusively(Native Method) ~[na:1.8.0_74]
    at java.io.File.createNewFile(File.java:1012) ~[na:1.8.0_74]
    at org.locationtech.geogig.storage.fs.IniFileConfigDatabase$2.iniFile(IniFileConfigDatabase.java:61) ~[geogig-core-1.0-RC1a.jar:1.0-RC1a]
    ... 18 common frames omitted
An unhandled error occurred: java.io.IOException: Permission denied. See the log for more details.

有人有主意吗？感谢