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All rights reserved. 49.\" Copyright 2020 Joyent, Inc. 50.\" Copyright 2022 Oxide Computer Company 51.\" 52.Dd February 5, 2022 53.Dt OPEN 2 54.Os 55.Sh NAME 56.Nm open , 57.Nm openat 58.Nd open a file 59.Sh SYNOPSIS 60.In sys/types.h 61.In sys/stat.h 62.In fcntl.h 63.Ft int 64.Fo open 65.Fa "const char *path" 66.Fa "int oflag" 67.Op , Fa "mode_t mode" 68.Fc 69.Ft int 70.Fo openat 71.Fa "int fildes" 72.Fa "const char *path" 73.Fa "int oflag" 74.Op , Fa "mode_t mode" 75.Fc 76.Sh DESCRIPTION 77The 78.Fn open 79function establishes the connection between a file and a file descriptor. 80It creates an open file description that refers to a file and a file descriptor 81that refers to that open file description. 82The file descriptor is used by other I/O functions to refer to that file. 83The 84.Fa path 85argument points to a pathname naming the file. 86.Pp 87The 88.Fn openat 89function is identical to the 90.Fn open 91function except 92that the 93.Fa path 94argument is interpreted relative to the starting point 95implied by the 96.Fa fildes 97argument. 98If the 99.Fa fildes 100argument has the special value 101.Dv AT_FDCWD , 102a relative path argument will be resolved relative to the current working 103directory. 104If the 105.Fa path 106argument is absolute, the 107.Fa fildes 108argument is ignored. 109.Pp 110The 111.Fn open 112function returns a file descriptor for the named file that is the lowest file 113descriptor not currently open for that process. 114The open file description is new, and therefore the file descriptor does not 115share it with any other process in the system. 116The 117.Dv FD_CLOEXEC 118file descriptor flag associated with the new file descriptor is cleared. 119.Pp 120The file offset used to mark the current position within the file is set to the 121beginning of the file. 122.Pp 123The file status flags and file access modes of the open file description are 124set according to the value of 125.Fa oflag . 126The 127.Fa mode 128argument is used only 129when 130.Dv O_CREAT 131is specified 132.Pq "see below" . 133.Pp 134Values for 135.Fa oflag 136are constructed by a bitwise-inclusive-OR of flags from 137the following list, defined in 138.Xr fcntl.h 3HEAD . 139Applications must specify exactly one of the first three values (file access 140modes) below in the value of 141.Fa oflag : 142.Bl -tag -width Ds 143.It Dv O_RDONLY 144Open for reading only. 145.It Dv O_WRONLY 146Open for writing only. 147.It Dv O_RDWR 148Open for reading and writing. 149The result is undefined if this flag is applied to a FIFO. 150.El 151.Pp 152Any combination of the following may be used: 153.Bl -tag -width Ds 154.It Dv O_APPEND 155If set, the file offset is set to the end of the file prior to each write. 156.It Dv O_CREAT 157Create the file if it does not exist. 158This flag requires that the 159.Fa mode 160argument be specified. 161.Pp 162If the file exists, this flag has no effect except as noted under 163.Dv O_EXCL 164below. 165Otherwise, the file is created with the user ID of the file set to the 166effective user ID of the process. 167The group ID of the file is set to the effective group IDs of the process, or 168if the 169.Dv S_ISGID 170bit is set in the directory in which the file is being created, the file's 171group ID is set to the group ID of its parent directory. 172If the group ID of the new file does not match the effective group 173ID or one of the supplementary groups IDs, the 174.Dv S_ISGID bit is cleared. 175.Pp 176The access permission bits 177.Po 178see 179.Xr stat.h 3HEAD 180.Pc 181of the file mode are set to the value of 182.Fa mode , 183modified as follows 184.Po 185see 186.Xr creat 2 187.Pc : 188a bitwise-AND is performed on the file-mode bits and the corresponding bits in 189the complement of the process's file mode creation mask. 190Thus, all bits set in the process's file mode creation mask 191.Po 192see 193.Xr umask 2 194.Pc 195are correspondingly cleared in the file's permission mask. 196The 197.Dq save text image after execution bit 198of the mode is cleared 199.Po 200see 201.Xr chmod 2 202.Pc . 203When bits other than the file permission bits are set, the effect is 204unspecified. 205The 206.Fa mode 207argument does not affect whether the file is open for reading, writing or for 208both. 209.It Dv O_DIRECT 210Indicates that the file data is not going to be reused in the near future. 211When possible, data is read or written directly between the application's 212memory and the device when the data is accessed with 213.Xr read 2 214and 215.Xr write 2 216operations. 217See 218.Xr directio 3C 219for more details. 220.It Dv O_DIRECTORY 221Indicates that attempts to open 222.Fa path 223should fail unless 224.Fa path 225is a directory. 226If both 227.Dv O_CREAT 228and 229.Dv O_DIRECTORY 230are specified then the call will fail if it would result in a file being 231created. 232If a directory already exists at 233.Fa path 234then it will behave as if the 235.Dv O_DIRECTORY 236flag had not been present. 237If the 238.Dv O_EXCL 239and 240.Dv O_CREAT 241flags are specified, then the call will always fail as they imply a file should 242always be created. 243.It Dv O_DSYNC 244Write I/O operations on the file descriptor complete as defined by synchronized 245I/O data integrity completion. 246.It Dv O_EXCL 247If 248.Dv O_CREAT 249and 250.Dv O_EXCL 251are set, 252.Fn open 253fails if the file exists. 254The check for the existence of the file and the creation of the file if 255it does not exist is atomic with respect to other threads executing 256.Fn open 257naming the same filename in the same directory with 258.Dv O_EXCL 259and 260.Dv O_CREAT 261set. 262If 263.Dv O_EXCL 264and 265.Dv O_CREAT 266are set, and 267.Fa path 268names a symbolic link, 269.Fn open 270fails and sets 271.Va errno 272to 273.Er EEXIST , 274regardless of the contents of the symbolic link. 275If 276.Dv O_EXCL 277is set and 278.Dv O_CREAT 279is not set, the result is undefined. 280.It Dv O_EXEC 281If set, indicates that the file should be opened for execute permission. 282This option is only valid for regular files; an error will be returned if the 283target is not a regular file. 284.It Dv O_LARGEFILE 285If set, the offset maximum in the open file description is the largest value 286that can be represented correctly in an object of type 287.Vt off64_t . 288.It Dv O_NOCTTY 289If set and 290.Fa path 291identifies a terminal device, 292.Fn open 293does not cause the terminal device to become the controlling terminal for the 294process. 295.It Dv O_NOFOLLOW 296If the path names a symbolic link, 297.Fn open 298fails and sets 299.Va errno 300to 301.Er ELOOP . 302.It Dv O_NOLINKS 303If the link count of the named file is greater than 304.Sy 1 , 305.Fn open 306fails and sets 307.Va errno 308to 309.Er EMLINK . 310.It Dv O_CLOEXEC 311If set, the file descriptor returned will be closed prior to any future 312.Xr exec 2 313calls. 314.It Dv O_NONBLOCK O_NDELAY 315These flags can affect subsequent reads and writes 316.Po 317see 318.Xr read 2 319and 320.Xr write 2 321.Pc . 322If both 323.Dv O_NDELAY 324and 325.Dv O_NONBLOCK 326are set, 327.Dv O_NONBLOCK 328takes precedence. 329.Pp 330When opening a FIFO with 331.Dv O_RDONLY 332or 333.Dv O_WRONLY 334set: 335.Bl -bullet 336.It 337If 338.Dv O_NONBLOCK 339or 340.Dv O_NDELAY 341is set, an 342.Fn open 343for reading only returns without delay. 344An 345.Fn open 346for writing only returns an error if no process currently has the file open for 347reading. 348.It 349If 350.Dv O_NONBLOCK 351and 352.Dv O_NDELAY 353are clear, an 354.Fn open 355for reading only blocks until a thread opens the file for writing. 356An 357.Fn open 358for writing only blocks the calling thread until a thread opens the file for 359reading. 360.El 361.Pp 362After both ends of a FIFO have been opened once, there is no guarantee that 363further calls to 364.Fn open 365.Dv O_RDONLY 366.Pq Dv O_WRONLY 367will synchronize with later calls to 368.Fn open 369.Dv O_WRONLY 370.Pq Dv O_RDONLY 371until both ends of the FIFO have been closed by all readers and writers. 372Any data written into a FIFO will be lost if both ends of the FIFO are closed 373before the data is read. 374.Pp 375When opening a block special or character special file that supports 376non-blocking opens: 377.Bl -bullet 378.It 379If 380.Dv O_NONBLOCK 381or 382.Dv O_NDELAY 383is set, the 384.Fn open 385function returns without blocking for the device to be ready or available. 386Subsequent behavior of the device is device-specific. 387.It 388If 389.Dv O_NONBLOCK 390and 391.Dv O_NDELAY 392are clear, the 393.Fn open 394function blocks the calling thread until the device is ready or available 395before returning. 396.El 397.Pp 398Otherwise, the behavior of 399.Dv O_NONBLOCK 400and 401.Dv O_NDELAY 402is unspecified. 403.It Dv O_RSYNC 404Read I/O operations on the file descriptor complete at the same level of 405integrity as specified by the 406.Dv O_DSYNC 407and 408.Dv O_SYNC 409flags. 410If both 411.Dv O_DSYNC 412and 413.Dv O_RSYNC 414are set in 415.Fa oflag , 416all I/O operations on the file descriptor complete as defined by synchronized 417I/O data integrity completion. 418If both 419.Dv O_SYNC 420and 421.Dv O_RSYNC 422are set in 423.Fa oflag , 424all I/O operations on the file descriptor complete as defined by synchronized 425I/O file integrity completion. 426.It Dv O_SEARCH 427If set, indicates that the directory should be opened for searching. 428This option is only valid for a directory; an error will be returned if the 429target is not a directory. 430.It Dv O_SYNC 431Write I/O operations on the file descriptor complete as defined by synchronized 432I/O file integrity completion 433.Po 434see 435.Xr fcntl.h 3HEAD 436.Pc 437definition of 438.Dv O_SYNC . 439.It Dv O_TRUNC 440If the file exists and is a regular file, and the file is successfully opened 441.Dv O_RDWR 442or 443.Dv O_WRONLY , 444its length is truncated to 445.Sy 0 446and the mode and owner are unchanged. 447It has no effect on FIFO special files or terminal device files. 448Its effect on other file types is implementation-dependent. 449The result of using 450.Dv O_TRUNC 451with 452.Dv O_RDONLY 453is undefined. 454.It Dv O_XATTR 455If set in 456.Fn openat , 457a relative path argument is interpreted as a reference to an extended attribute 458of the file associated with the supplied file descriptor. 459This flag therefore requires the presence of a legal 460.Fa fildes 461argument. 462If set in 463.Fn open , 464the implied file descriptor is that for the current working directory. 465Extended attributes must be referenced with a relative path; providing an 466absolute path results in a normal file reference. 467.El 468.Pp 469If 470.Dv O_CREAT 471is set and the file did not previously exist, upon successful completion, 472.Fn open 473marks for update the 474.Fa st_atime , 475.Fa st_ctime , 476and 477.Fa st_mtime 478fields of the file and the 479.Fa st_ctime 480and 481.Fa st_mtime 482fields of the parent directory. 483.Pp 484If 485.Dv O_TRUNC 486is set and the file did previously exist, upon successful completion, 487.Fn open 488marks for update the 489.Fa st_ctime 490and 491.Fa st_mtime 492fields of the file. 493.Pp 494If both the 495.Dv O_SYNC 496and 497.Dv O_DSYNC 498flags are set, the effect is as if only the 499.Dv O_SYNC 500flag was set. 501.Pp 502If 503.Fa path 504refers to a STREAMS file, 505.Fa oflag 506may be constructed from 507.Dv O_NONBLOCK 508or 509.Dv O_NODELAY 510OR-ed with either 511.Dv O_RDONLY , 512.Dv O_WRONLY , 513or 514.Dv O_RDWR . 515Other flag values are not applicable to STREAMS devices and have no effect on 516them. 517The values 518.Dv O_NONBLOCK 519and 520.Dv O_NODELAY 521affect the operation of STREAMS drivers and certain functions 522.Po 523see 524.Xr read 2 , 525.Xr getmsg 2 , 526.Xr putmsg 2 , 527and 528.Xr write 2 529.Pc 530applied to file descriptors associated with STREAMS files. 531For STREAMS drivers, the implementation of 532.Dv O_NONBLOCK 533and 534.Dv O_NODELAY 535is device-specific. 536.Pp 537When 538.Fn open 539is invoked to open a named stream, and the 540.Xr connld 7M 541module has been pushed on the pipe, 542.Fn open 543blocks until the server process has issued an 544.Dv I_RECVFD 545.Xr ioctl 2 546.Po 547see 548.Xr streamio 7I 549.Pc 550to receive the file descriptor. 551.Pp 552If 553.Fa path 554names the manager side of a pseudo-terminal device, then it is unspecified 555whether 556.Fn open 557locks the subsidiary side so that it cannot be opened. 558Portable applications must call 559.Xr unlockpt 3C 560before opening the subsidiary side. 561.Pp 562If the file is a regular file and the local file system is mounted with the 563.Cm nbmand 564mount option, then a mandatory share reservation is automatically obtained on 565the file. 566The share reservation is obtained as if 567.Xr fcntl 2 568were called with 569.Fa cmd 570.Dv F_SHARE_NBMAND 571and the 572.Vt fshare_t 573values set as follows: 574.Bl -tag -width Ds -offset Ds 575.It Fa f_access 576Set to the type of read/write access for which the file is opened. 577.It Fa f_deny 578.Dv F_NODNY 579.It Fa f_id 580The file descriptor value returned from 581.Fn open . 582.El 583.Pp 584If 585.Fa path 586is a symbolic link and 587.Dv O_CREAT 588and 589.Dv O_EXCL 590are set, the link is not followed. 591.Pp 592Certain flag values can be set following 593.Fn open 594as described in 595.Xr fcntl 2 . 596.Pp 597The largest value that can be represented correctly in an object of type 598.Vt off_t 599is established as the offset maximum in the open file description. 600.Sh RETURN VALUES 601The 602.Fn open 603and 604.Fn openat 605functions open the file and, if successful, return a non-negative integer 606representing the lowest numbered unused file descriptor; otherwise the 607value 608.Sy -1 609is returned and the global variable 610.Va errno 611is set to indicate the error and no files are created or modified. 612.Sh EXAMPLES 613.Sy Example 1 614Open a file for writing by the owner. 615.Pp 616The following example opens the file 617.Pa /tmp/file , 618either by creating it if it does not already exist, or by truncating its length 619to 620.Sy 0 621if it does exist. 622If the call creates a new file, the access permission bits in the file mode of 623the file are set to permit reading and writing by the owner, and to permit 624reading only by group members and others. 625.Pp 626If the call to 627.Fn open 628is successful, the file is opened for writing. 629.Bd -literal -offset Ds 630#include <fcntl.h> 631\&... 632int fd; 633mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH; 634char *filename = "/tmp/file"; 635\&... 636fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, mode); 637\&... 638.Ed 639.Pp 640.Sy Example 2 641Open a file using an existence check. 642.Pp 643The following example uses the 644.Fn open 645function to try to create the 646.Dv LOCKFILE 647file and open it for writing. 648Since the 649.Fn open 650function specifies the 651.Dv O_EXCL 652flag, the call fails if the file already exists. 653In that case, the application assumes that someone else is updating the 654password file and exits. 655.Bd -literal -offset Ds 656#include <fcntl.h> 657#include <stdio.h> 658#include <stdlib.h> 659#include <err.h> 660\&... 661#define LOCKFILE "/etc/ptmp" 662\&... 663int pfd; /* Integer for file descriptor returned by open() call. */ 664\&... 665if ((pfd = open(LOCKFILE, O_WRONLY | O_CREAT | O_EXCL, 666 S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)) < 0) { 667 err(1, "Cannot open %s. Try again later.", LOCKFILE); 668} 669\&... 670.Ed 671.Pp 672.Sy Example 3 673Open a file for writing. 674.Pp 675The following example opens a file for writing, creating the file if it does 676not already exist. 677If the file does exist, the system truncates the file to zero bytes. 678.Bd -literal -offset Ds 679#include <fcntl.h> 680#include <stdio.h> 681#include <stdlib.h> 682#include <err.h> 683\&... 684int pfd; 685char filename[PATH_MAX+1]; 686\&... 687if ((pfd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 688 S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)) < 0) { 689 err(1, "Cannot open output file"); 690} 691\&... 692.Ed 693.Sh ERRORS 694The 695.Fn open 696and 697.Fn openat 698functions will fail if: 699.Bl -tag -width Er 700.It Er EACCES 701Search permission is denied on a component of the path prefix. 702.Pp 703The file exists and the permissions specified by 704.Fa oflag 705are denied. 706.Pp 707The file does not exist and write permission is denied for the parent directory 708of the file to be created. 709.Pp 710.Dv O_TRUNC 711is specified and write permission is denied. 712.Pp 713The 714.Brq Dv PRIV_FILE_DAC_SEARCH 715privilege allows processes to search directories regardless of permission bits. 716The 717.Brq Dv PRIV_FILE_DAC_WRITE 718privilege allows processes to open files for writing regardless of permission 719bits. 720See 721.Xr privileges 5 for special considerations when opening files owned by user ID 722.Sy 0 723for writing. 724The 725.Brq Dv PRIV_FILE_DAC_READ 726privilege allows 727processes to open files for reading regardless of permission bits. 728.It Er EAGAIN 729A mandatory share reservation could not be obtained because the desired access 730conflicts with an existing 731.Fa f_deny 732share reservation 733.Po 734see 735.Xr fcntl 2 736.Pc . 737.It Er EDQUOT 738The file does not exist, 739.Dv O_CREAT 740is specified, and either the directory where the new file entry is being placed 741cannot be extended because the user's quota of disk blocks on that file system 742has been exhausted, or the user's quota of inodes on the file system where the 743file is being created has been exhausted. 744.It Er EEXIST 745The 746.Dv O_CREAT 747and 748.Dv O_EXCL 749flags are set and the named file already exists. 750.It Er EILSEQ 751The 752.Fa path 753argument includes bytes that are not valid UTF-8 characters, and the file 754system accepts only file names where all characters are part of the UTF-8 755character codeset. 756.It Er EINTR 757A signal was caught during 758.Fn open . 759.It Er EFAULT 760The 761.Fa path 762argument points to an illegal address. 763.It Er EINVAL 764Either the system does not support synchronized or direct I/O for this file, or 765the 766.Dv O_XATTR 767flag was supplied and the underlying file system does not support extended file 768attributes. 769.It Er EIO 770The 771.Fa path 772argument names a STREAMS file and a hangup or error occurred during the 773.Fn open . 774.It Er EISDIR 775The named file is a directory and 776.Fa oflag 777includes 778.Dv O_WRONLY 779or 780.Dv O_RDWR . 781.It Er ELOOP 782Too many symbolic links were encountered in resolving 783.Fa path . 784.Pp 785A loop exists in symbolic links encountered during resolution of the 786.Fa path 787argument. 788.Pp 789The 790.Dv O_NOFOLLOW 791flag is set and the final component of path is a symbolic link. 792.It Er EMFILE 793There are currently 794.Brq Dv OPEN_MAX 795file descriptors open in the calling process. 796.It Er EMLINK 797The 798.Dv O_NOLINKS 799flag is set and the named file has a link count greater than 800.Sy 1 . 801.It Er EMULTIHOP 802Components of 803.Fa path 804require hopping to multiple remote machines and the file system does not allow 805it. 806.It Er ENAMETOOLONG 807The length of the 808.Fa path 809argument exceeds 810.Brq Dv PATH_MAX 811or a pathname component is longer than 812.Brq Dv NAME_MAX . 813.It Er ENFILE 814The maximum allowable number of files is currently open in the system. 815.It Er ENOENT 816The 817.Dv O_CREAT 818flag is not set and the named file does not exist; or the 819.Dv O_CREAT 820flag is set and either the path prefix does not exist or the 821.Fa path 822argument points to an empty string. 823.Pp 824The 825.Dv O_CREAT 826and 827.Dv O_DIRECTORY 828flags were both set and 829.Fa path 830did not point to a file. 831.It Er ENOEXEC 832The 833.Dv O_EXEC 834flag is set and 835.Fa path 836does not point to a regular file. 837.It Er ENOLINK 838The 839.Fa path 840argument points to a remote machine, and the link to that machine is no longer 841active. 842.It Er ENOSR 843Th 844.Fa path 845argument names a STREAMS-based file and the system is unable to allocate a 846STREAM. 847.It Er ENOSPC 848The directory or file system that would contain the new file cannot be 849expanded, the file does not exist, and 850.Dv O_CREAT 851is specified. 852.It Er ENOSYS 853The device specified by 854.Fa path 855does not support the open operation. 856.It Er ENOTDIR 857A component of the path prefix is not a directory or a relative path was 858supplied to 859.Fn openat , 860the 861.Dv O_XATTR 862flag was not supplied, and the file descriptor does not refer to a directory. 863The 864.Dv O_SEARCH 865flag was passed and 866.Fa path 867does not refer to a directory. 868.Pp 869The 870.Dv O_DIRECTORY 871flag was set and the file was not a directory. 872.It Er ENXIO 873The 874.Dv O_NONBLOCK 875flag is set, the named file is a FIFO, the 876.Dv O_WRONLY 877flag is set, and no process has the file open for reading; or the named file is 878a character special or block special file and the device associated with this 879special file does not exist or has been retired by the fault management 880framework. 881.It Er EOPNOTSUPP 882An attempt was made to open a path that corresponds to an 883.Dv AF_UNIX 884socket. 885.It Er EOVERFLOW 886The named file is a regular file and either 887.Dv O_LARGEFILE 888is not set and the size of the file cannot be represented correctly in an 889object of type 890.Vt off_t 891or 892.Dv O_LARGEFILE 893is set and the size of the file cannot be represented correctly in an object of 894type 895.Vt off64_t . 896.It Er EROFS 897The named file resides on a read-only file system and either 898.Dv O_WRONLY , 899.Dv O_RDWR , 900.Dv O_CREAT 901(if file does not exist), or 902.Dv O_TRUNC 903is set in the 904.Fa oflag 905argument. 906.El 907.Pp 908The 909.Fn openat 910function will fail if: 911.Bl -tag -width Er 912.It Er EBADF 913The 914.Fa fildes 915argument is not a valid open file descriptor or is not 916.Dv AT_FTCWD . 917.El 918.Pp 919The 920.Fn open 921function may fail if: 922.Bl -tag -width Er 923.It Er EAGAIN 924The 925.Fa path 926argument names the subsidiary side of a pseudo-terminal device that is locked. 927.It Er EINVAL 928The value of the 929.Fa oflag 930argument is not valid. 931.It Er ENAMETOOLONG 932Pathname resolution of a symbolic link produced an intermediate result whose 933length exceeds 934.Brq Dv PATH_MAX . 935.It Er ENOMEM 936The 937.Fa path 938argument names a STREAMS file and the system is unable to allocate resources. 939.It Er ETXTBSY 940The file is a pure procedure (shared text) file that is being executed and 941.Fa oflag 942is 943.Dv O_WRONLY 944or 945.Dv O_RDWR . 946.El 947.Sh USAGE 948The 949.Fn open 950function has a transitional interface for 64-bit file offsets. 951See 952.Xr lf64 5 . 953Note that using 954.Fn open64 955is equivalent to using 956.Fn open with 957.Dv O_LARGEFILE 958set in 959.Fa oflag . 960.Sh INTERFACE STABILITY 961.Sy Committed 962.Sh MT LEVEL 963.Sy Async-Signal-Safe 964.Sh SEE ALSO 965.Xr chmod 2 , 966.Xr close 2 , 967.Xr creat 2 , 968.Xr dup 2 , 969.Xr exec 2 , 970.Xr fcntl 2 , 971.Xr getmsg 2 , 972.Xr getrlimit 2 , 973.Xr Intro 2 , 974.Xr lseek 2 , 975.Xr putmsg 2 , 976.Xr read 2 , 977.Xr stat 2 , 978.Xr umask 2 , 979.Xr write 2 , 980.Xr attropen 3C , 981.Xr directio 3C , 982.Xr unlockpt 3C , 983.Xr fcntl.h 3HEAD , 984.Xr stat.h 3HEAD , 985.Xr attributes 5 , 986.Xr lf64 5 , 987.Xr privileges 5 , 988.Xr standards 5 , 989.Xr streamio 7I , 990.Xr connld 7M 991.Sh NOTES 992Hierarchical Storage Management 993.Pq HSM 994file systems can sometimes cause long delays when opening a file, since HSM 995files must be recalled from secondary storage. 996