1# Virtual File System<a name="EN-US_TOPIC_0000001123796667"></a> 2 3- [Basic Concepts](#section1253851143520) 4- [Working Principles](#section14915913123510) 5- [Development Guidelines](#section1759563620358) 6 - [Available APIs](#section17865142133511) 7 - [How to Develop](#section64113023616) 8 - [Development Example](#section236041883618) 9 10 11## Basic Concepts<a name="section1253851143520"></a> 12 13The Virtual File System \(VFS\) is not a real file system. It is an abstract layer on top of a heterogeneous file system and provides you with a unified Unix-like file operation interface. Different types of file systems provide different interfaces. If there are multiple types of file systems in the system, different and non-standard interfaces are required for accessing these file systems. The VFS can be introduced as an abstract layer in the system to harmonize the differences between these heterogeneous file systems. In this way, the system does not need to care about the storage medium and file system type at the bottom layer when accessing a file system. 14 15In the OpenHarmony kernel, the VFS framework is implemented through the tree structure in the memory. Each node of the tree is a **Vnode** structure, and the relationship between the parent and child nodes is stored in the **PathCache** structure. The VFS provides the following functions: 16 17- Node query 18- Unified file system invoking \(standard\) 19 20## Working Principles<a name="section14915913123510"></a> 21 22The VFS layer uses function pointers to call different interfaces for different types of file systems to implement standard APIs. It uses the Vnode and PathCache mechanisms to improve path search and file access performance, manages partitions through mount point management, and isolates File Descriptors \(FDs\) between processes through FD management. These mechanisms are briefly described below. 23 241. File system function pointer: The VFS uses function pointers to distribute calls to different file systems for underlying operations based on the file system type. Each file system implements a set of Vnode operation, mount point operation, and file operation APIs, and stores them in the corresponding Vnode, mount point, and file structures in the form of function pointer structures, so that the VFS layer can access the Vnode, mount point, and file structures. 252. Vnode: A Vnode is an abstract encapsulation of a specific file or directory at the VFS layer. It shields the differences between different file systems and implements unified resource management. Vnodes include the following types: 26 27 - Mount point: used to mount a specific file system, for example, **/** and **/storage**. 28 - Device node: mapping to a device in the **/dev** directory, for example, **/dev/mmcblk0** 29 - File/Directory node: corresponds to a file or directory in a file system, for example, **/bin/init**. 30 31 Vnodes are managed using the hash and least recently used \(LRU\) mechanisms. After a system is started, the Vnode cache is preferentially searched in the hash linked list for an access request for a file or directory. If the cache is not hit, the target file or directory is searched in the corresponding file system, and the corresponding Vnode is created and cached. When the number of cached Vnodes reaches the upper limit, the Vnodes that are not accessed for a long time will be deleted. The mount point Vnodes and device node Vnodes are not deleted. The default number of Vnodes in the system is 512. You can configure the value in **LOSCFG\_MAX\_VNODE\_SIZE**. Increasing the value can improve search performance but cause high memory usage. The following figure shows the process of creating a Vnode. 32 33 **Figure 1** Process of creating a Vnode<a name="fig1453197573"></a> 34  35 36 371. PathCache: The PathCache is a path cache. It is stored in a hash table. Based on the address of the parent Vnode and the file name of the child node in the PathCache, the Vnode corresponding to the child node can be quickly found. The following figure shows how a file or directory is located. 38 39 **Figure 2** Process of locating a file<a name="fig1881815597396"></a> 40  41 42 431. PageCache: The PageCache is a cache of files in the kernel. Currently, the PageCache can cache only binary files. When a file is accessed for the first time, the file is mapped to the memory using **mmap**. When the file is accessed the next time, the file can be directly read from the PageCache, accelerating the read and write speed of the file. In addition, page cache helps implement IPC based on files. 442. FD management: A FD uniquely identifies an open file or directory in an OS. The OpenHarmony has 896 FDs, which include the following: 45 46 - 512 file descriptors 47 - 128 socket descriptors 48 - 256 message queue descriptors 49 50 In the OpenHarmony kernel, the FDs of different processes are isolated. That is, a process can access only its own FD. The FDs of all processes are mapped to a global FD table for unified allocation and management. The maximum number of process file descriptors is 256. 51 523. Mount point management: The OpenHarmony kernel manages all mount points in a linked list. The mount point structure records all Vnodes in the mounted partition. When a partition is unmounted, all Vnodes in the partition are released. 53 54## Development Guidelines<a name="section1759563620358"></a> 55 56### Available APIs<a name="section17865142133511"></a> 57 58In the following table, "×" indicates that the corresponding file system does not support the API. 59 60**Table 1** File system APIs 61 62<a name="table17301515163415"></a> 63<table><thead align="left"><tr id="row1730115183416"><th class="cellrowborder" valign="top" width="22.547745225477453%" id="mcps1.2.9.1.1"><p id="p830131563412"><a name="p830131563412"></a><a name="p830131563412"></a>Category</p> 64</th> 65<th class="cellrowborder" valign="top" width="22.547745225477453%" id="mcps1.2.9.1.2"><p id="p43011512345"><a name="p43011512345"></a><a name="p43011512345"></a>API</p> 66</th> 67<th class="cellrowborder" valign="top" width="22.547745225477453%" id="mcps1.2.9.1.3"><p id="p1130101519342"><a name="p1130101519342"></a><a name="p1130101519342"></a>Description</p> 68</th> 69<th class="cellrowborder" valign="top" width="5.499450054994501%" id="mcps1.2.9.1.4"><p id="p107591639173415"><a name="p107591639173415"></a><a name="p107591639173415"></a>FAT</p> 70</th> 71<th class="cellrowborder" valign="top" width="5.949405059494051%" id="mcps1.2.9.1.5"><p id="p540384933412"><a name="p540384933412"></a><a name="p540384933412"></a>JFFS2</p> 72</th> 73<th class="cellrowborder" valign="top" width="6.419358064193579%" id="mcps1.2.9.1.6"><p id="p1912513588343"><a name="p1912513588343"></a><a name="p1912513588343"></a>NFS</p> 74</th> 75<th class="cellrowborder" valign="top" width="6.95930406959304%" id="mcps1.2.9.1.7"><p id="p1057755183515"><a name="p1057755183515"></a><a name="p1057755183515"></a>TMPFS</p> 76</th> 77<th class="cellrowborder" valign="top" width="7.529247075292471%" id="mcps1.2.9.1.8"><p id="p25201318183510"><a name="p25201318183510"></a><a name="p25201318183510"></a>PROCFS</p> 78</th> 79</tr> 80</thead> 81<tbody><tr id="row53018152343"><td class="cellrowborder" rowspan="16" valign="top" width="22.547745225477453%" headers="mcps1.2.9.1.1 "><p id="p151510381154"><a name="p151510381154"></a><a name="p151510381154"></a>File management</p> 82</td> 83<td class="cellrowborder" valign="top" width="22.547745225477453%" headers="mcps1.2.9.1.2 "><p id="p5302152348"><a name="p5302152348"></a><a name="p5302152348"></a>open</p> 84</td> 85<td class="cellrowborder" valign="top" width="22.547745225477453%" headers="mcps1.2.9.1.3 "><p id="p8301815103412"><a name="p8301815103412"></a><a name="p8301815103412"></a>Opens a file.</p> 86</td> 87<td class="cellrowborder" valign="top" width="5.499450054994501%" headers="mcps1.2.9.1.4 "><p id="p294710215329"><a name="p294710215329"></a><a name="p294710215329"></a>√</p> 88</td> 89<td class="cellrowborder" valign="top" width="5.949405059494051%" headers="mcps1.2.9.1.5 "><p id="p9261258325"><a name="p9261258325"></a><a name="p9261258325"></a>√</p> 90</td> 91<td class="cellrowborder" valign="top" width="6.419358064193579%" headers="mcps1.2.9.1.6 "><p id="p1531472803219"><a name="p1531472803219"></a><a name="p1531472803219"></a>√</p> 92</td> 93<td class="cellrowborder" valign="top" width="6.95930406959304%" headers="mcps1.2.9.1.7 "><p id="p1081010131337"><a name="p1081010131337"></a><a name="p1081010131337"></a>√</p> 94</td> 95<td class="cellrowborder" valign="top" width="7.529247075292471%" headers="mcps1.2.9.1.8 "><p id="p9730516133310"><a name="p9730516133310"></a><a name="p9730516133310"></a>√</p> 96</td> 97</tr> 98<tr id="row1231181593416"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p1631141515344"><a name="p1631141515344"></a><a name="p1631141515344"></a>read/pread/readv/preadv</p> 99</td> 100<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p731115173413"><a name="p731115173413"></a><a name="p731115173413"></a>Reads a file.</p> 101</td> 102<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p49398914559"><a name="p49398914559"></a><a name="p49398914559"></a>√</p> 103</td> 104<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p17960592553"><a name="p17960592553"></a><a name="p17960592553"></a>√</p> 105</td> 106<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p69811093556"><a name="p69811093556"></a><a name="p69811093556"></a>√</p> 107</td> 108<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p1599119915554"><a name="p1599119915554"></a><a name="p1599119915554"></a>√</p> 109</td> 110<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p121101016557"><a name="p121101016557"></a><a name="p121101016557"></a>√</p> 111</td> 112</tr> 113<tr id="row631215173419"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p1312013310440"><a name="p1312013310440"></a><a name="p1312013310440"></a>write/pwrite/writev/pwritev</p> 114</td> 115<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p1631201513418"><a name="p1631201513418"></a><a name="p1631201513418"></a>Writes a file.</p> 116</td> 117<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p1210121018551"><a name="p1210121018551"></a><a name="p1210121018551"></a>√</p> 118</td> 119<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p1120710185512"><a name="p1120710185512"></a><a name="p1120710185512"></a>√</p> 120</td> 121<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p1529510185513"><a name="p1529510185513"></a><a name="p1529510185513"></a>√</p> 122</td> 123<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p133911014559"><a name="p133911014559"></a><a name="p133911014559"></a>√</p> 124</td> 125<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p94881019559"><a name="p94881019559"></a><a name="p94881019559"></a>√</p> 126</td> 127</tr> 128<tr id="row13820154164814"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p1982084154815"><a name="p1982084154815"></a><a name="p1982084154815"></a>lseek</p> 129</td> 130<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p18201148481"><a name="p18201148481"></a><a name="p18201148481"></a>Sets the file offset.</p> 131</td> 132<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p1477251395513"><a name="p1477251395513"></a><a name="p1477251395513"></a>√</p> 133</td> 134<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p979119136551"><a name="p979119136551"></a><a name="p979119136551"></a>√</p> 135</td> 136<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p138102013175517"><a name="p138102013175517"></a><a name="p138102013175517"></a>√</p> 137</td> 138<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p482041319556"><a name="p482041319556"></a><a name="p482041319556"></a>√</p> 139</td> 140<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p4667132210334"><a name="p4667132210334"></a><a name="p4667132210334"></a>×</p> 141</td> 142</tr> 143<tr id="row18311215103413"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p29893124420"><a name="p29893124420"></a><a name="p29893124420"></a>close</p> 144</td> 145<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p16317151345"><a name="p16317151345"></a><a name="p16317151345"></a>Closes a file.</p> 146</td> 147<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p1830101311552"><a name="p1830101311552"></a><a name="p1830101311552"></a>√</p> 148</td> 149<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p083916133557"><a name="p083916133557"></a><a name="p083916133557"></a>√</p> 150</td> 151<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p7848141318556"><a name="p7848141318556"></a><a name="p7848141318556"></a>√</p> 152</td> 153<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p98581213135515"><a name="p98581213135515"></a><a name="p98581213135515"></a>√</p> 154</td> 155<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p1422632414334"><a name="p1422632414334"></a><a name="p1422632414334"></a>√</p> 156</td> 157</tr> 158<tr id="row1775494216429"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p2755144216427"><a name="p2755144216427"></a><a name="p2755144216427"></a>unlink</p> 159</td> 160<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p1475534213424"><a name="p1475534213424"></a><a name="p1475534213424"></a>Deletes a file.</p> 161</td> 162<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p11868171355516"><a name="p11868171355516"></a><a name="p11868171355516"></a>√</p> 163</td> 164<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p78771813175517"><a name="p78771813175517"></a><a name="p78771813175517"></a>√</p> 165</td> 166<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p488641355510"><a name="p488641355510"></a><a name="p488641355510"></a>√</p> 167</td> 168<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p12895121315517"><a name="p12895121315517"></a><a name="p12895121315517"></a>√</p> 169</td> 170<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p51901414341"><a name="p51901414341"></a><a name="p51901414341"></a>×</p> 171</td> 172</tr> 173<tr id="row730533465319"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p134325815218"><a name="p134325815218"></a><a name="p134325815218"></a>fstat</p> 174</td> 175<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p03438583528"><a name="p03438583528"></a><a name="p03438583528"></a>Queries file information.</p> 176</td> 177<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p190418132555"><a name="p190418132555"></a><a name="p190418132555"></a>√</p> 178</td> 179<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p109131713145518"><a name="p109131713145518"></a><a name="p109131713145518"></a>√</p> 180</td> 181<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p20922161345511"><a name="p20922161345511"></a><a name="p20922161345511"></a>√</p> 182</td> 183<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p129311134558"><a name="p129311134558"></a><a name="p129311134558"></a>√</p> 184</td> 185<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p1634395895213"><a name="p1634395895213"></a><a name="p1634395895213"></a>√</p> 186</td> 187</tr> 188<tr id="row12854143815611"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p12854123817564"><a name="p12854123817564"></a><a name="p12854123817564"></a>fallocate</p> 189</td> 190<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p158541938165619"><a name="p158541938165619"></a><a name="p158541938165619"></a>Pre-allocates a file.</p> 191</td> 192<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p2092312119324"><a name="p2092312119324"></a><a name="p2092312119324"></a>√</p> 193</td> 194<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p58541638155611"><a name="p58541638155611"></a><a name="p58541638155611"></a>×</p> 195</td> 196<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p485410387565"><a name="p485410387565"></a><a name="p485410387565"></a>×</p> 197</td> 198<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p9250515446"><a name="p9250515446"></a><a name="p9250515446"></a>×</p> 199</td> 200<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p12178113643319"><a name="p12178113643319"></a><a name="p12178113643319"></a>×</p> 201</td> 202</tr> 203<tr id="row231161563416"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p15311154341"><a name="p15311154341"></a><a name="p15311154341"></a>truncate</p> 204</td> 205<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p73111513417"><a name="p73111513417"></a><a name="p73111513417"></a>Truncates a file.</p> 206</td> 207<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p4553163085512"><a name="p4553163085512"></a><a name="p4553163085512"></a>√</p> 208</td> 209<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p155722303558"><a name="p155722303558"></a><a name="p155722303558"></a>√</p> 210</td> 211<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p01250585343"><a name="p01250585343"></a><a name="p01250585343"></a>×</p> 212</td> 213<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p815106143319"><a name="p815106143319"></a><a name="p815106143319"></a>√</p> 214</td> 215<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p20697173810337"><a name="p20697173810337"></a><a name="p20697173810337"></a>×</p> 216</td> 217</tr> 218<tr id="row931815133419"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p63151593415"><a name="p63151593415"></a><a name="p63151593415"></a>link</p> 219</td> 220<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p1631101523414"><a name="p1631101523414"></a><a name="p1631101523414"></a>Creates a hard link.</p> 221</td> 222<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p18718522143115"><a name="p18718522143115"></a><a name="p18718522143115"></a>×</p> 223</td> 224<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p1147101520321"><a name="p1147101520321"></a><a name="p1147101520321"></a>√</p> 225</td> 226<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p17125185815342"><a name="p17125185815342"></a><a name="p17125185815342"></a>×</p> 227</td> 228<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p1985892113312"><a name="p1985892113312"></a><a name="p1985892113312"></a>×</p> 229</td> 230<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p17342840113315"><a name="p17342840113315"></a><a name="p17342840113315"></a>×</p> 231</td> 232</tr> 233<tr id="row131151523420"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p113251513342"><a name="p113251513342"></a><a name="p113251513342"></a>symlink</p> 234</td> 235<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p1832215133420"><a name="p1832215133420"></a><a name="p1832215133420"></a>Creates a soft link.</p> 236</td> 237<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p5780143585510"><a name="p5780143585510"></a><a name="p5780143585510"></a>√</p> 238</td> 239<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p1879183525516"><a name="p1879183525516"></a><a name="p1879183525516"></a>√</p> 240</td> 241<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p412505873415"><a name="p412505873415"></a><a name="p412505873415"></a>×</p> 242</td> 243<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p13207802451"><a name="p13207802451"></a><a name="p13207802451"></a>×</p> 244</td> 245<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p1947920415337"><a name="p1947920415337"></a><a name="p1947920415337"></a>×</p> 246</td> 247</tr> 248<tr id="row382917545412"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p158308546414"><a name="p158308546414"></a><a name="p158308546414"></a>readlink</p> 249</td> 250<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p58301454144111"><a name="p58301454144111"></a><a name="p58301454144111"></a>Reads a soft link.</p> 251</td> 252<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p14802935155512"><a name="p14802935155512"></a><a name="p14802935155512"></a>√</p> 253</td> 254<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p8812193535516"><a name="p8812193535516"></a><a name="p8812193535516"></a>√</p> 255</td> 256<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p68301754134120"><a name="p68301754134120"></a><a name="p68301754134120"></a>×</p> 257</td> 258<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p132078004517"><a name="p132078004517"></a><a name="p132078004517"></a>×</p> 259</td> 260<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p147954143315"><a name="p147954143315"></a><a name="p147954143315"></a>×</p> 261</td> 262</tr> 263<tr id="row1511111910388"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p143496410465"><a name="p143496410465"></a><a name="p143496410465"></a>dup</p> 264</td> 265<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p17349942461"><a name="p17349942461"></a><a name="p17349942461"></a>Copies a file handle.</p> 266</td> 267<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p1299875075513"><a name="p1299875075513"></a><a name="p1299875075513"></a>√</p> 268</td> 269<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p5183517557"><a name="p5183517557"></a><a name="p5183517557"></a>√</p> 270</td> 271<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p133845110558"><a name="p133845110558"></a><a name="p133845110558"></a>√</p> 272</td> 273<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p15488511558"><a name="p15488511558"></a><a name="p15488511558"></a>√</p> 274</td> 275<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p15817510554"><a name="p15817510554"></a><a name="p15817510554"></a>√</p> 276</td> 277</tr> 278<tr id="row512919173399"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p350604555614"><a name="p350604555614"></a><a name="p350604555614"></a>fsync</p> 279</td> 280<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p12506184516569"><a name="p12506184516569"></a><a name="p12506184516569"></a>Saves the update of a file to a device.</p> 281</td> 282<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p13875181213213"><a name="p13875181213213"></a><a name="p13875181213213"></a>√</p> 283</td> 284<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p0506145165613"><a name="p0506145165613"></a><a name="p0506145165613"></a>×</p> 285</td> 286<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p6506124555620"><a name="p6506124555620"></a><a name="p6506124555620"></a>×</p> 287</td> 288<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p1925165204418"><a name="p1925165204418"></a><a name="p1925165204418"></a>×</p> 289</td> 290<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p1795065310333"><a name="p1795065310333"></a><a name="p1795065310333"></a>×</p> 291</td> 292</tr> 293<tr id="row11374165313411"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p3724551105613"><a name="p3724551105613"></a><a name="p3724551105613"></a>ioctl</p> 294</td> 295<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p8724165112564"><a name="p8724165112564"></a><a name="p8724165112564"></a>Controls a device.</p> 296</td> 297<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p8724251165616"><a name="p8724251165616"></a><a name="p8724251165616"></a>×</p> 298</td> 299<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p2725185119569"><a name="p2725185119569"></a><a name="p2725185119569"></a>×</p> 300</td> 301<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p6725125118565"><a name="p6725125118565"></a><a name="p6725125118565"></a>×</p> 302</td> 303<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p172511584419"><a name="p172511584419"></a><a name="p172511584419"></a>√</p> 304</td> 305<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p795045363314"><a name="p795045363314"></a><a name="p795045363314"></a>×</p> 306</td> 307</tr> 308<tr id="row1566230193619"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p8804322192315"><a name="p8804322192315"></a><a name="p8804322192315"></a>fcntl</p> 309</td> 310<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p2891723102316"><a name="p2891723102316"></a><a name="p2891723102316"></a>Performs file control operations.</p> 311</td> 312<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p16968175595517"><a name="p16968175595517"></a><a name="p16968175595517"></a>√</p> 313</td> 314<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p69788557556"><a name="p69788557556"></a><a name="p69788557556"></a>√</p> 315</td> 316<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p4987135555516"><a name="p4987135555516"></a><a name="p4987135555516"></a>√</p> 317</td> 318<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p1599755565514"><a name="p1599755565514"></a><a name="p1599755565514"></a>√</p> 319</td> 320<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p551453173620"><a name="p551453173620"></a><a name="p551453173620"></a>√</p> 321</td> 322</tr> 323<tr id="row98781157114116"><td class="cellrowborder" rowspan="17" valign="top" width="22.547745225477453%" headers="mcps1.2.9.1.1 "><p id="p10322754163618"><a name="p10322754163618"></a><a name="p10322754163618"></a>Directory management</p> 324</td> 325<td class="cellrowborder" valign="top" width="22.547745225477453%" headers="mcps1.2.9.1.2 "><p id="p98795579417"><a name="p98795579417"></a><a name="p98795579417"></a>mkdir</p> 326</td> 327<td class="cellrowborder" valign="top" width="22.547745225477453%" headers="mcps1.2.9.1.3 "><p id="p12879757144119"><a name="p12879757144119"></a><a name="p12879757144119"></a>Creates a directory.</p> 328</td> 329<td class="cellrowborder" valign="top" width="5.499450054994501%" headers="mcps1.2.9.1.4 "><p id="p1361756205516"><a name="p1361756205516"></a><a name="p1361756205516"></a>√</p> 330</td> 331<td class="cellrowborder" valign="top" width="5.949405059494051%" headers="mcps1.2.9.1.5 "><p id="p717956115512"><a name="p717956115512"></a><a name="p717956115512"></a>√</p> 332</td> 333<td class="cellrowborder" valign="top" width="6.419358064193579%" headers="mcps1.2.9.1.6 "><p id="p32813566552"><a name="p32813566552"></a><a name="p32813566552"></a>√</p> 334</td> 335<td class="cellrowborder" valign="top" width="6.95930406959304%" headers="mcps1.2.9.1.7 "><p id="p537115611555"><a name="p537115611555"></a><a name="p537115611555"></a>√</p> 336</td> 337<td class="cellrowborder" valign="top" width="7.529247075292471%" headers="mcps1.2.9.1.8 "><p id="p9879165719415"><a name="p9879165719415"></a><a name="p9879165719415"></a>×</p> 338</td> 339</tr> 340<tr id="row362155116544"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p166210511546"><a name="p166210511546"></a><a name="p166210511546"></a>opendir</p> 341</td> 342<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p11621651135417"><a name="p11621651135417"></a><a name="p11621651135417"></a>Opens a directory.</p> 343</td> 344<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p1863161175612"><a name="p1863161175612"></a><a name="p1863161175612"></a>√</p> 345</td> 346<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p16655191105612"><a name="p16655191105612"></a><a name="p16655191105612"></a>√</p> 347</td> 348<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p267518118566"><a name="p267518118566"></a><a name="p267518118566"></a>√</p> 349</td> 350<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p18686011561"><a name="p18686011561"></a><a name="p18686011561"></a>√</p> 351</td> 352<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p369611105616"><a name="p369611105616"></a><a name="p369611105616"></a>√</p> 353</td> 354</tr> 355<tr id="row183271724212"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p23313179429"><a name="p23313179429"></a><a name="p23313179429"></a>readdir</p> 356</td> 357<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p1433617124218"><a name="p1433617124218"></a><a name="p1433617124218"></a>Reads a directory.</p> 358</td> 359<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p1470631135613"><a name="p1470631135613"></a><a name="p1470631135613"></a>√</p> 360</td> 361<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p0715810565"><a name="p0715810565"></a><a name="p0715810565"></a>√</p> 362</td> 363<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p67251414566"><a name="p67251414566"></a><a name="p67251414566"></a>√</p> 364</td> 365<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p14734511565"><a name="p14734511565"></a><a name="p14734511565"></a>√</p> 366</td> 367<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p1474419165617"><a name="p1474419165617"></a><a name="p1474419165617"></a>√</p> 368</td> 369</tr> 370<tr id="row11310111512553"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p183101215155514"><a name="p183101215155514"></a><a name="p183101215155514"></a>closedir</p> 371</td> 372<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p2031018155555"><a name="p2031018155555"></a><a name="p2031018155555"></a>Closes a directory.</p> 373</td> 374<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p177544125617"><a name="p177544125617"></a><a name="p177544125617"></a>√</p> 375</td> 376<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p576311175619"><a name="p576311175619"></a><a name="p576311175619"></a>√</p> 377</td> 378<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p18772171115612"><a name="p18772171115612"></a><a name="p18772171115612"></a>√</p> 379</td> 380<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p1978310112562"><a name="p1978310112562"></a><a name="p1978310112562"></a>√</p> 381</td> 382<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p27921517569"><a name="p27921517569"></a><a name="p27921517569"></a>√</p> 383</td> 384</tr> 385<tr id="row1774355219252"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p1074365218251"><a name="p1074365218251"></a><a name="p1074365218251"></a>telldir</p> 386</td> 387<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p5743125232520"><a name="p5743125232520"></a><a name="p5743125232520"></a>Obtains the directory offset.</p> 388</td> 389<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p1880251135614"><a name="p1880251135614"></a><a name="p1880251135614"></a>√</p> 390</td> 391<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p681110105618"><a name="p681110105618"></a><a name="p681110105618"></a>√</p> 392</td> 393<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p1682112135612"><a name="p1682112135612"></a><a name="p1682112135612"></a>√</p> 394</td> 395<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p1583019165610"><a name="p1583019165610"></a><a name="p1583019165610"></a>√</p> 396</td> 397<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p148397175618"><a name="p148397175618"></a><a name="p148397175618"></a>√</p> 398</td> 399</tr> 400<tr id="row463867132610"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p463919772612"><a name="p463919772612"></a><a name="p463919772612"></a>seekdir</p> 401</td> 402<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p163917702620"><a name="p163917702620"></a><a name="p163917702620"></a>Sets the directory offset.</p> 403</td> 404<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p08494113563"><a name="p08494113563"></a><a name="p08494113563"></a>√</p> 405</td> 406<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p19858121175618"><a name="p19858121175618"></a><a name="p19858121175618"></a>√</p> 407</td> 408<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p16867131175616"><a name="p16867131175616"></a><a name="p16867131175616"></a>√</p> 409</td> 410<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p487621145618"><a name="p487621145618"></a><a name="p487621145618"></a>√</p> 411</td> 412<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p1088611118566"><a name="p1088611118566"></a><a name="p1088611118566"></a>√</p> 413</td> 414</tr> 415<tr id="row1361903616456"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p186191936144513"><a name="p186191936144513"></a><a name="p186191936144513"></a>rewinddir</p> 416</td> 417<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p186198365451"><a name="p186198365451"></a><a name="p186198365451"></a>Resets the directory offset.</p> 418</td> 419<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p82717515564"><a name="p82717515564"></a><a name="p82717515564"></a>√</p> 420</td> 421<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p1128175145610"><a name="p1128175145610"></a><a name="p1128175145610"></a>√</p> 422</td> 423<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p729113545616"><a name="p729113545616"></a><a name="p729113545616"></a>√</p> 424</td> 425<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p163003585620"><a name="p163003585620"></a><a name="p163003585620"></a>√</p> 426</td> 427<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p10950175314334"><a name="p10950175314334"></a><a name="p10950175314334"></a>×</p> 428</td> 429</tr> 430<tr id="row1145016117201"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p9545171282019"><a name="p9545171282019"></a><a name="p9545171282019"></a>scandir</p> 431</td> 432<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p9451131102012"><a name="p9451131102012"></a><a name="p9451131102012"></a>Reads directory data.</p> 433</td> 434<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p230917512566"><a name="p230917512566"></a><a name="p230917512566"></a>√</p> 435</td> 436<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p1831815155615"><a name="p1831815155615"></a><a name="p1831815155615"></a>√</p> 437</td> 438<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p53275555611"><a name="p53275555611"></a><a name="p53275555611"></a>√</p> 439</td> 440<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p1033611512565"><a name="p1033611512565"></a><a name="p1033611512565"></a>√</p> 441</td> 442<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p345131118206"><a name="p345131118206"></a><a name="p345131118206"></a>√</p> 443</td> 444</tr> 445<tr id="row623472084218"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p92341220134219"><a name="p92341220134219"></a><a name="p92341220134219"></a>rmdir</p> 446</td> 447<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p1234220144217"><a name="p1234220144217"></a><a name="p1234220144217"></a>Deletes a directory.</p> 448</td> 449<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p1034615175618"><a name="p1034615175618"></a><a name="p1034615175618"></a>√</p> 450</td> 451<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p123567595611"><a name="p123567595611"></a><a name="p123567595611"></a>√</p> 452</td> 453<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p63654555619"><a name="p63654555619"></a><a name="p63654555619"></a>√</p> 454</td> 455<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p1737485135619"><a name="p1737485135619"></a><a name="p1737485135619"></a>√</p> 456</td> 457<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p179508533337"><a name="p179508533337"></a><a name="p179508533337"></a>×</p> 458</td> 459</tr> 460<tr id="row1991017101176"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p09101210171712"><a name="p09101210171712"></a><a name="p09101210171712"></a>chdir</p> 461</td> 462<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p1091014106172"><a name="p1091014106172"></a><a name="p1091014106172"></a>Changes the current directory.</p> 463</td> 464<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p1338219545610"><a name="p1338219545610"></a><a name="p1338219545610"></a>√</p> 465</td> 466<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p173911585618"><a name="p173911585618"></a><a name="p173911585618"></a>√</p> 467</td> 468<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p13400053567"><a name="p13400053567"></a><a name="p13400053567"></a>√</p> 469</td> 470<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p2040916516565"><a name="p2040916516565"></a><a name="p2040916516565"></a>√</p> 471</td> 472<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p497687155612"><a name="p497687155612"></a><a name="p497687155612"></a>√</p> 473</td> 474</tr> 475<tr id="row735414923319"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p19181108339"><a name="p19181108339"></a><a name="p19181108339"></a>getcwd</p> 476</td> 477<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p19354129143316"><a name="p19354129143316"></a><a name="p19354129143316"></a>Obtains the current directory.</p> 478</td> 479<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p5419165105610"><a name="p5419165105610"></a><a name="p5419165105610"></a>√</p> 480</td> 481<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p64281059561"><a name="p64281059561"></a><a name="p64281059561"></a>√</p> 482</td> 483<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p174375585616"><a name="p174375585616"></a><a name="p174375585616"></a>√</p> 484</td> 485<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p5446452567"><a name="p5446452567"></a><a name="p5446452567"></a>√</p> 486</td> 487<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p5986171564"><a name="p5986171564"></a><a name="p5986171564"></a>√</p> 488</td> 489</tr> 490<tr id="row080771185710"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p19826155733610"><a name="p19826155733610"></a><a name="p19826155733610"></a>realpath</p> 491</td> 492<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p766310254365"><a name="p766310254365"></a><a name="p766310254365"></a>Converts between the relative and absolute paths.</p> 493</td> 494<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p04551758568"><a name="p04551758568"></a><a name="p04551758568"></a>√</p> 495</td> 496<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p124644516565"><a name="p124644516565"></a><a name="p124644516565"></a>√</p> 497</td> 498<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p204731052562"><a name="p204731052562"></a><a name="p204731052562"></a>√</p> 499</td> 500<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p34822575610"><a name="p34822575610"></a><a name="p34822575610"></a>√</p> 501</td> 502<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p2996107145611"><a name="p2996107145611"></a><a name="p2996107145611"></a>√</p> 503</td> 504</tr> 505<tr id="row194318220214"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p153666165451"><a name="p153666165451"></a><a name="p153666165451"></a>rename</p> 506</td> 507<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p1136671615455"><a name="p1136671615455"></a><a name="p1136671615455"></a>Renames a file or directory.</p> 508</td> 509<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p349119515619"><a name="p349119515619"></a><a name="p349119515619"></a>√</p> 510</td> 511<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p95004515561"><a name="p95004515561"></a><a name="p95004515561"></a>√</p> 512</td> 513<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p6509253569"><a name="p6509253569"></a><a name="p6509253569"></a>√</p> 514</td> 515<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p155199525619"><a name="p155199525619"></a><a name="p155199525619"></a>√</p> 516</td> 517<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p3342940193313"><a name="p3342940193313"></a><a name="p3342940193313"></a>×</p> 518</td> 519</tr> 520<tr id="row944217272374"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p1044272714376"><a name="p1044272714376"></a><a name="p1044272714376"></a>chmod</p> 521</td> 522<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p1044214273374"><a name="p1044214273374"></a><a name="p1044214273374"></a>Modifies the file or directory property.</p> 523</td> 524<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p43281412135617"><a name="p43281412135617"></a><a name="p43281412135617"></a>√</p> 525</td> 526<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p1234641219566"><a name="p1234641219566"></a><a name="p1234641219566"></a>√</p> 527</td> 528<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p17442927123717"><a name="p17442927123717"></a><a name="p17442927123717"></a>×</p> 529</td> 530<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p1644262714375"><a name="p1644262714375"></a><a name="p1644262714375"></a>×</p> 531</td> 532<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p1844218271376"><a name="p1844218271376"></a><a name="p1844218271376"></a>×</p> 533</td> 534</tr> 535<tr id="row74691154211"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p1747111124210"><a name="p1747111124210"></a><a name="p1747111124210"></a>chown</p> 536</td> 537<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p0471911114215"><a name="p0471911114215"></a><a name="p0471911114215"></a>Changes the file or directory owner.</p> 538</td> 539<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p836713125561"><a name="p836713125561"></a><a name="p836713125561"></a>√</p> 540</td> 541<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p12377171265616"><a name="p12377171265616"></a><a name="p12377171265616"></a>√</p> 542</td> 543<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p122061697438"><a name="p122061697438"></a><a name="p122061697438"></a>×</p> 544</td> 545<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p2206159114316"><a name="p2206159114316"></a><a name="p2206159114316"></a>×</p> 546</td> 547<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p920609134316"><a name="p920609134316"></a><a name="p920609134316"></a>×</p> 548</td> 549</tr> 550<tr id="row1036123420529"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p730583495314"><a name="p730583495314"></a><a name="p730583495314"></a>stat/lstat</p> 551</td> 552<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p1630513410532"><a name="p1630513410532"></a><a name="p1630513410532"></a>Queries file or directory information.</p> 553</td> 554<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p338719123568"><a name="p338719123568"></a><a name="p338719123568"></a>√</p> 555</td> 556<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p113961712125612"><a name="p113961712125612"></a><a name="p113961712125612"></a>√</p> 557</td> 558<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p19388161745612"><a name="p19388161745612"></a><a name="p19388161745612"></a>√</p> 559</td> 560<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p163981517185615"><a name="p163981517185615"></a><a name="p163981517185615"></a>√</p> 561</td> 562<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p16287141955616"><a name="p16287141955616"></a><a name="p16287141955616"></a>√</p> 563</td> 564</tr> 565<tr id="row16466943145113"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p4871175874615"><a name="p4871175874615"></a><a name="p4871175874615"></a>access</p> 566</td> 567<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p187125818465"><a name="p187125818465"></a><a name="p187125818465"></a>Queries the access permission on a file or directory.</p> 568</td> 569<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p240531211562"><a name="p240531211562"></a><a name="p240531211562"></a>√</p> 570</td> 571<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p141515129564"><a name="p141515129564"></a><a name="p141515129564"></a>√</p> 572</td> 573<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p1640821725613"><a name="p1640821725613"></a><a name="p1640821725613"></a>√</p> 574</td> 575<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p114181417125618"><a name="p114181417125618"></a><a name="p114181417125618"></a>√</p> 576</td> 577<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p1829741985617"><a name="p1829741985617"></a><a name="p1829741985617"></a>√</p> 578</td> 579</tr> 580<tr id="row780042214211"><td class="cellrowborder" rowspan="5" valign="top" width="22.547745225477453%" headers="mcps1.2.9.1.1 "><p id="p206804542364"><a name="p206804542364"></a><a name="p206804542364"></a>Partition management</p> 581</td> 582<td class="cellrowborder" valign="top" width="22.547745225477453%" headers="mcps1.2.9.1.2 "><p id="p1380192264218"><a name="p1380192264218"></a><a name="p1380192264218"></a>mount</p> 583</td> 584<td class="cellrowborder" valign="top" width="22.547745225477453%" headers="mcps1.2.9.1.3 "><p id="p38011522104210"><a name="p38011522104210"></a><a name="p38011522104210"></a>Mounts a partition.</p> 585</td> 586<td class="cellrowborder" valign="top" width="5.499450054994501%" headers="mcps1.2.9.1.4 "><p id="p10424191245618"><a name="p10424191245618"></a><a name="p10424191245618"></a>√</p> 587</td> 588<td class="cellrowborder" valign="top" width="5.949405059494051%" headers="mcps1.2.9.1.5 "><p id="p24341126561"><a name="p24341126561"></a><a name="p24341126561"></a>√</p> 589</td> 590<td class="cellrowborder" valign="top" width="6.419358064193579%" headers="mcps1.2.9.1.6 "><p id="p3428151785614"><a name="p3428151785614"></a><a name="p3428151785614"></a>√</p> 591</td> 592<td class="cellrowborder" valign="top" width="6.95930406959304%" headers="mcps1.2.9.1.7 "><p id="p12437111785613"><a name="p12437111785613"></a><a name="p12437111785613"></a>√</p> 593</td> 594<td class="cellrowborder" valign="top" width="7.529247075292471%" headers="mcps1.2.9.1.8 "><p id="p4307161913563"><a name="p4307161913563"></a><a name="p4307161913563"></a>√</p> 595</td> 596</tr> 597<tr id="row4684182822512"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p1468412813252"><a name="p1468412813252"></a><a name="p1468412813252"></a>umount</p> 598</td> 599<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p26846284258"><a name="p26846284258"></a><a name="p26846284258"></a>Unmounts a partition.</p> 600</td> 601<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p044321275614"><a name="p044321275614"></a><a name="p044321275614"></a>√</p> 602</td> 603<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p84531312125615"><a name="p84531312125615"></a><a name="p84531312125615"></a>√</p> 604</td> 605<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p244720173564"><a name="p244720173564"></a><a name="p244720173564"></a>√</p> 606</td> 607<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p104571517155619"><a name="p104571517155619"></a><a name="p104571517155619"></a>√</p> 608</td> 609<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p173412575334"><a name="p173412575334"></a><a name="p173412575334"></a>×</p> 610</td> 611</tr> 612<tr id="row5177163172511"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p617843117252"><a name="p617843117252"></a><a name="p617843117252"></a>statfs</p> 613</td> 614<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p181781531192519"><a name="p181781531192519"></a><a name="p181781531192519"></a>Queries information about a mounted partition.</p> 615</td> 616<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p144623124566"><a name="p144623124566"></a><a name="p144623124566"></a>√</p> 617</td> 618<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p1747251235611"><a name="p1747251235611"></a><a name="p1747251235611"></a>√</p> 619</td> 620<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p446813179565"><a name="p446813179565"></a><a name="p446813179565"></a>√</p> 621</td> 622<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p147781716561"><a name="p147781716561"></a><a name="p147781716561"></a>√</p> 623</td> 624<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p4178133182515"><a name="p4178133182515"></a><a name="p4178133182515"></a>√</p> 625</td> 626</tr> 627<tr id="row1769881513348"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p156992015143419"><a name="p156992015143419"></a><a name="p156992015143419"></a>format</p> 628</td> 629<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p16935183513394"><a name="p16935183513394"></a><a name="p16935183513394"></a>Formats a partition.</p> 630</td> 631<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p19289615195611"><a name="p19289615195611"></a><a name="p19289615195611"></a>√</p> 632</td> 633<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p14186550113916"><a name="p14186550113916"></a><a name="p14186550113916"></a>×</p> 634</td> 635<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p382435053911"><a name="p382435053911"></a><a name="p382435053911"></a>×</p> 636</td> 637<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p1246615123918"><a name="p1246615123918"></a><a name="p1246615123918"></a>×</p> 638</td> 639<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p13818525391"><a name="p13818525391"></a><a name="p13818525391"></a>×</p> 640</td> 641</tr> 642<tr id="row4270132114219"><td class="cellrowborder" valign="top" headers="mcps1.2.9.1.1 "><p id="p958455012219"><a name="p958455012219"></a><a name="p958455012219"></a>sync</p> 643</td> 644<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.2 "><p id="p125840501224"><a name="p125840501224"></a><a name="p125840501224"></a>Saves the partition information to a device.</p> 645</td> 646<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.3 "><p id="p8300115125612"><a name="p8300115125612"></a><a name="p8300115125612"></a>√</p> 647</td> 648<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.4 "><p id="p25044812404"><a name="p25044812404"></a><a name="p25044812404"></a>×</p> 649</td> 650<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.5 "><p id="p17501248184019"><a name="p17501248184019"></a><a name="p17501248184019"></a>×</p> 651</td> 652<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.6 "><p id="p1850154824012"><a name="p1850154824012"></a><a name="p1850154824012"></a>×</p> 653</td> 654<td class="cellrowborder" valign="top" headers="mcps1.2.9.1.7 "><p id="p18505483404"><a name="p18505483404"></a><a name="p18505483404"></a>×</p> 655</td> 656</tr> 657</tbody> 658</table> 659 660### How to Develop<a name="section64113023616"></a> 661 662The file system development process involves mounting and unmounting partitions and managing directories and files. 663 664### Development Example<a name="section236041883618"></a> 665 666The sample code is as follows: 667 668``` 669#include <stdio.h> 670#include <string.h> 671#include "sys/stat.h" 672#include "fcntl.h" 673#include "unistd.h" 674 675#define LOS_OK 0 676#define LOS_NOK -1 677 678int main(void) 679{ 680 int ret; 681 int fd = -1; 682 ssize_t len; 683 off_t off; 684 char mntName[20] = "/storage"; 685 char devName[20] = "/dev/mmcblk0p0"; 686 char dirName[20] = "/storage/test"; 687 char fileName[20] = "/storage/test/file.txt"; 688 char writeBuf[20] = "Hello OpenHarmony!"; 689 char readBuf[20] = {0}; 690 691 /* Create the directory /storage. 692 ret = mkdir(mntName, 0777); 693 if (ret != LOS_OK) { 694 printf("mkdir failed.\n"); 695 return LOS_NOK; 696 } 697 698 /* Mount the /dev/mmcblk0p0 device to the /storage directory.*/ 699 ret = mount(devName, mntName, "vfat", 0, 0); 700 if (ret != LOS_OK) { 701 printf("mount failed.\n"); 702 return LOS_NOK; 703 } 704 705 /* Create the directory /storage/test. 706 ret = mkdir(dirName, 0777); 707 if (ret != LOS_OK) { 708 printf("mkdir failed.\n"); 709 return LOS_NOK; 710 } 711 712 /* Create the file /storage/test/file.txt and make it readable and writable.*/ 713 fd = open(fileName, O_RDWR | O_CREAT, 0777); 714 if (fd < 0) { 715 printf("open file failed.\n"); 716 return LOS_NOK; 717 } 718 719 /* Write the content from writeBuf to the file. */ 720 len = write(fd, writeBuf, strlen(writeBuf)); 721 if (len != strlen(writeBuf)) { 722 printf("write file failed.\n"); 723 return LOS_NOK; 724 } 725 726 /* Save the update of the file to the storage device.*/ 727 ret = fsync(fd); 728 if (ret != LOS_OK) { 729 printf("fsync failed.\n"); 730 return LOS_NOK; 731 } 732 733 /* Move the read/write pointer to the file header. */ 734 off = lseek(fd, 0, SEEK_SET); 735 if (off != 0) { 736 printf("lseek failed.\n"); 737 return LOS_NOK; 738 } 739 740 /* Read the file content, with the same size as readBuf, to readBuf.*/ 741 len = read(fd, readBuf, sizeof(readBuf)); 742 if (len != strlen(readBuf)) { 743 printf("read file failed.\n"); 744 return LOS_NOK; 745 } 746 printf("%s\n", readBuf); 747 748 /* Close the file. */ 749 ret = close(fd); 750 if (ret != LOS_OK) { 751 printf("close failed.\n"); 752 return LOS_NOK; 753 } 754 755 /*Delete the file /storage/test/file.txt.*/ 756 ret = unlink(fileName); 757 if (ret != LOS_OK) { 758 printf("unlink failed.\n"); 759 return LOS_NOK; 760 } 761 762 /*Delete the /storage/test directory.*/ 763 ret = rmdir(dirName); 764 if (ret != LOS_OK) { 765 printf("rmdir failed.\n"); 766 return LOS_NOK; 767 } 768 769 /* Unmount the /storage partition.*/ 770 ret = umount(mntName); 771 if (ret != LOS_OK) { 772 printf("umount failed.\n"); 773 return LOS_NOK; 774 } 775 776 /*Delete the /storage/ directory.*/ 777 ret = rmdir(mntName); 778 if (ret != LOS_OK) { 779 printf("rmdir failed.\n"); 780 return LOS_NOK; 781 } 782 783 return LOS_OK; 784} 785``` 786 787**Verification** 788 789The development is successful if the return result is as follows: 790 791``` 792Hello OpenHarmony! 793``` 794 795
