Allow quoting of arguments to the CYGWIN environment variable, i.e., set CYGWIN=error_start="c:\bin\someprogram -T"
Console screen clearing works more like xterm or mintty.
popen now supports the Glibc 'e' flag to set the FD_CLOEXEC flag on the pipe in a thread-safe way.
New netinet/ip6.h header.
Switch to BSD FILE stream fopen/exit semantics, as in all BSD variants and Linux/GLibc: Don't fflush/lseek a FILE stream on fclose and exit, if it only has been read from.
Don't create native symlinks with target paths having long path prefixes "\\?\" if the target path is shorter than MAX_PATH characters. This works around a Windows 8.1 bug: The ShellExecuteW fails if the lpFile parameter points to a native NTFS symlink with a target path prefixed with "\\?\".
getaddrinfo now supports glibc-specific International Domain Name (IDN) extension flags: AI_IDN, AI_CANONIDN, AI_IDN_ALLOW_UNASSIGNED, AI_IDN_USE_STD3_ASCII_RULES.
getnameinfo now supports glibc-specific International Domain Name (IDN) extension flags: NI_IDN, NI_IDN_ALLOW_UNASSIGNED, NI_IDN_USE_STD3_ASCII_RULES.
Slightly improve randomness of /dev/random emulation.
Allow to use advisory locking on any device. POSIX fcntl and lockf locking works with any device, BSD flock locking only with devices backed by an OS handle. Right now this excludes console windows on pre Windows 8, as well as almost all virtual files under /proc from BSD flock locking.
The header /usr/include/exceptions.h, containing implementation details for 32 bit Windows' exception handling only, has been removed.
Preliminary, experimental support of the posix_spawn family of functions. New associated header /usr/include/spawn.h.
Change magic number associated with process information block so that 32-bit Cygwin processes don't try to interpret 64-bit information and vice-versa.
Redefine content of mtget tape info struct to allow fetching the number of partitions on a tape.
Added CYGWIN environment variable keyword "wincmdln" which causes Cygwin to send the full windows command line to any subprocesses.
Support for /dev/mem, /dev/kmem and /dev/port removed, since OS support was limited to 32 bit Windows XP only.
Added cygwin GetCommandLine wrappers which will allow Cygwin programs to (appear to) use the Windows command line functions.
regcomp(3) now allows character values >= 0x80 if the current codeset is ASCII (default codeset in the "C"/"POSIX" locale). This allows patterns containing arbitrary byte values as GLibc's regcomp.
Drop support for Windows 2000 and Windows XP pre-SP3.
Add support for building a 64 bit version of Cygwin on x86_64 natively.
Add support for creating native NTFS symlinks starting with Windows Vista by setting the CYGWIN=winsymlinks:native or CYGWIN=winsymlinks:nativestrict option.
Add support for AFS filesystem.
Preliminary support for mandatory locking via fcntl/flock/lockf, using Windows locking semantics. New F_LCK_MANDATORY fcntl command.
New APIs: __b64_ntop, __b64_pton, arc4random, arc4random_addrandom, arc4random_buf, arc4random_stir, arc4random_uniform.
Added Windows console cursor appearance support.
Show/Hide Cursor mode (DECTCEM): "ESC[?25h" / "ESC[?25l"
Set cursor style (DECSCUSR): "ESC[n q" (note the space before the q); where n is 0, 1, 2 for block cursor, 3, 4 for underline cursor (all disregarding blinking mode), or > 4 to set the cursor height to a percentage of the cell height.
For performance reasons, Cygwin does not try to create sparse files automatically anymore, unless you use the new "sparse" mount option.
New API: cfsetspeed.
Support the "e" flag to fopen(3). This is a Glibc extension which allows to fopen the file with the O_CLOEXEC flag set.
Support the "x" flag to fopen(3). This is a Glibc/C11 extension which allows to open the file with the O_EXCL flag set.
New API: getmntent_r, memrchr.
Recognize ReFS filesystem.
CYGWIN=pipe_byte option now forces the opening of pipes in byte mode rather than message mode.
Add mouse reporting modes 1005, 1006 and 1015 to console window.
mkpasswd and mkgroup now try to print an entry for the TrustedInstaller account existing since Windows Vista/Server 2008.
Terminal typeahead when switching from canonical to non-canonical mode is now properly flushed.
Cygwin now automatically populates the /dev directory with all existing POSIX devices.
Add virtual /proc/PID/mountinfo file.
flock now additionally supports the following scenario, which requires to propagate locks to the parent process:
( flock -n 9 || exit 1 # ... commands executed under lock ... } 9>/var/lock/mylockfile
Only propagation to the direct parent process is supported so far, not to grand parents or sibling processes.
Add a "detect_bloda" setting for the CYGWIN environment variable to help finding potential BLODAs.
New pldd command for listing DLLs loaded by a process.
New API: scandirat.
Change the way remote shares mapped to drive letters are recognized when creating the cygdrive directory. If Windows claims the drive is unavailable, don't show it in the cygdrive directory listing.
Raise default stacksize of pthreads from 512K to 1 Meg. It can still be changed using the pthread_attr_setstacksize call.
Drop support for Windows NT4.
The CYGWIN environment variable options "envcache", "strip_title", "title", "tty", and "upcaseenv" have been removed.
If the executable (and the system) is large address aware, the application heap
will be placed in the large memory area. The peflags tool
rebase package can be used to set the large
address awareness flag in the executable file header.
The registry setting "heap_chunk_in_mb" has been removed, in favor of a new per-executable setting in the executable file header which can be set using the peflags tool. See the section called “Changing Cygwin's Maximum Memory” for more information.
The CYGWIN=tty mode using pipes to communicate with the console in a pseudo tty-like mode has been removed. Either just use the normal Windows console as is, or use a terminal application like mintty.
New getconf command for querying confstr(3), pathconf(3), sysconf(3), and limits.h configuration.
New tzset utility to generate a POSIX-compatible TZ environment variable from the Windows timezone settings.
The passwd command now allows an administrator to use the -R command for other user accounts: passwd -R username.
Pthread spinlocks. New APIs: pthread_spin_destroy, pthread_spin_init, pthread_spin_lock, pthread_spin_trylock, pthread_spin_unlock.
Pthread stack address management. New APIs: pthread_attr_getstack, pthread_attr_getstackaddr, pthread_attr_getguardsize, pthread_attr_setstack, pthread_attr_setstackaddr, pthread_attr_setguardsize, pthread_getattr_np.
POSIX Clock Selection option. New APIs: clock_nanosleep, pthread_condattr_getclock, pthread_condattr_setclock.
clock_gettime(3) and clock_getres(3) accept per-process and per-thread CPU-time clocks, including CLOCK_PROCESS_CPUTIME_ID and CLOCK_THREAD_CPUTIME_ID. New APIs: clock_getcpuclockid, pthread_getcpuclockid.
GNU/glibc error.h error reporting functions. New APIs: error, error_at_line. New exports: error_message_count, error_one_per_line, error_print_progname. Also, perror and strerror_r no longer clobber strerror storage.
C99 <tgmath.h> type-generic macros.
/proc/loadavg now shows the number of currently running processes and the total number of processes.
Added /proc/devices and /proc/misc, which lists supported device types and their device numbers.
Added /proc/swaps, which shows the location and size of Windows paging file(s).
Added /proc/sysvipc/msg, /proc/sysvipc/sem, and /proc/sysvipc/shm which provide information about System V IPC message queues, semaphores, and shared memory.
/proc/version now shows the username of whomever compiled the Cygwin DLL as well as the version of GCC used when compiling.
dlopen now supports the Glibc-specific RTLD_NODELETE and RTLD_NOOPEN flags.
The printf(3) and wprintf(3) families of functions now handle the %m conversion flag.
Other new API: clock_settime, __fpurge, getgrouplist, get_current_dir_name, getpt, ppoll, psiginfo, psignal, ptsname_r, sys_siglist, pthread_setschedprio, pthread_sigqueue, sysinfo.
Drop support for Windows NT4 prior to Service Pack 4.
Reinstantiate Cygwin's ability to delete an empty directory which is the current working directory of the same or another process. Same for any other empty directory which has been opened by the same or another process.
Cygwin now ships the C standard library fenv.h header file, and implements the related APIs (including GNU/glibc extensions): feclearexcept, fedisableexcept, feenableexcept, fegetenv, fegetexcept, fegetexceptflag, fegetprec, fegetround, feholdexcept, feraiseexcept, fesetenv, fesetexceptflag, fesetprec, fesetround, fetestexcept, feupdateenv, and predefines both default and no-mask FP environments. See the GNU C Library manual for full details of this functionality.
Support for the C99 complex functions, except for the "long double" implementations. New APIs: cacos, cacosf, cacosh, cacoshf, carg, cargf, casin, casinf, casinh, casinhf, catan, catanf, catanh, catanhf, ccos, ccosf, ccosh, ccoshf, cexp, cexpf, cimag, cimagf, clog, clogf, conj, conjf, cpow, cpowf, cproj, cprojf, creal, crealf, csin, csinf, csinh, csinhf, csqrt, csqrtf, ctan, ctanf, ctanh, ctanhf.
Fix the width of "CJK Ambiguous Width" characters to 1 for singlebyte charsets and 2 for East Asian multibyte charsets. (For UTF-8, it remains dependent on the specified language, and the "@cjknarrow" locale modifier can still be used to force width 1.)
The strerror_r interface now has two flavors; if _GNU_SOURCE is defined, it retains the previous behavior of returning char * (but the result is now guaranteed to be NUL-terminated); otherwise it now obeys POSIX semantics of returning int.
/proc/sys now allows unfiltered access to the native NT namespace. Access restrictions still apply. Direct device access via /proc/sys is not yet supported. File system access via block devices works. For instance (note the trailing slash!)
bash$ cd /proc/sys/Device/HarddiskVolumeShadowCopy1/
Other new APIs: llround, llroundf, madvise, pthread_yield. Export program_invocation_name, program_invocation_short_name. Support TIOCGPGRP, TIOCSPGRP ioctls.
Partially revert the 1.7.6 change to set the Win32 current working directory (CWD) always to an invalid directory, since it breaks backward compatibility too much. The Cygwin CWD and the Win32 CWD are now kept in sync again, unless the Cygwin CWD is not usable as Win32 CWD. See the reworked the section called “Using the Win32 file API in Cygwin applications” for details.
Make sure to follow the Microsoft security advisory concerning DLL hijacking. See the Microsoft Security Advisory (2269637) "Insecure Library Loading Could Allow Remote Code Execution" for details.
Allow to link against -lbinmode instead of /lib/binmode.o. Same for -ltextmode, -ltextreadmode and -lautomode. See the section called “Programming” for details.
Add new mount options "dos" and "ihash" to allow overriding Cygwin default behaviour on broken filesystems not recognized by Cygwin.
Add new mount option "bind" to allow remounting parts of the POSIX file hirarchy somewhere else.
Ttys and ptys are handled as securable objects using file-like permissions and owner/group information. chmod and chown now work on ttys/ptys. A new mechanism is used to propagate pty handles safely to other processes, which does not require to use Cygserver.
Pass on coresize settings made with setrlimit(2). This allows shells to disable creating stackdump files in child processes via
ulimit -c 0
in bash or
limit coredumpsize 0
Locale categories contain all localization strings additionally as wide-char strings. locale(1) prints these values just as on Linux. nl_langinfo(3) allows to fetch them.
New interfaces mkostemp(3) and mkostemps(3) are added.
New virtual file /proc/filesystems.
clock_gettime(3) and clock_getres(3) accept CLOCK_MONOTONIC.
DEPRECATED with 1.7.7: Cygwin handles the current working directory entirely on its own. The Win32 current working directory is set to an invalid path to be out of the way. [...]
Support for DEC Backarrow Key Mode escape sequences (ESC [ ? 67 h, ESC [ ? 67 l) in Windows console.
Support for GB2312/EUC-CN. These charsets are implemented as aliases to GBK. GB2312 is now the default charset name for the locales zh_CN and zh_SG, just as on Linux.
Modification and access timestamps of devices reflect the current time.
Localization support has been much improved.
Cygwin now handles locales using the underlying Windows locale support. The locale must exist in Windows to be recognized. Locale aliases from the file /usr/share/locale/locale.alias are also allowed, as long as their replacement is supported by the underlying Windows.
New tool "locale" to fetch locale information and default locales based on the Windows default settings as well as lists of all supported locales and character sets.
Default charset for locales without explicit charset is now chosen from a list of Linux-compatible charsets.
For instance: en_US -> ISO-8859-1, ja_JP -> EUC-JP, zh_TW -> Big5.
Added support for the charsets GEORGIAN-PS, PT154, and TIS-620.
Support for the various locale modifiers to switch charsets as on Linux.
Default charset in the "C" or "POSIX" locale has been changed back from UTF-8 to ASCII, to avoid problems with applications expecting a singlebyte charset in the "C"/"POSIX" locale. Still use UTF-8 internally for filename conversion in this case.
LC_COLLATE, LC_MONETARY, LC_NUMERIC, and LC_TIME localization is enabled via Windows locale support. LC_MESSAGES is enabled via a big table with localized strings.
fnmatch(3), regcomp(3), regexec(3) calls are now multibyte-aware.
printf(3), wprintf(3) families of functions now handle the grouping
flag, the apostrophe
', per POSIX-1.2008. The
integer portion of the result of a decimal conversion (%i, %d, %u, %f,
%F, %g, %G) will be formatted with thousands' grouping characters.
strftime(3), wcsftime(3), and strptime(3) now handle the E and O format modifiers to print/scan alternative date and time representations or to use alternative digits in locales which support this. Additionally these functions now also support the padding modifiers '0' and '+', as well as a field width per POSIX-1.2008.
New strfmon(3) call.
Support open(2) flags O_CLOEXEC and O_TTY_INIT flags. Support fcntl flag F_DUPFD_CLOEXEC. Support socket flags SOCK_CLOEXEC and SOCK_NONBLOCK. Add new Linux-compatible API calls accept4(2), dup3(2), and pipe2(2). Support the signal SIGPWR.
Enhanced Windows console support.
The console's backspace keycode can be changed using 'stty erase'.
Function keys send distinguished escape sequences compatible with rxvt. Keypad keys send distinguished escape sequences, xterm-style.
Support of combining Alt and AltGr modifiers in console window (compatible with xterm and mintty), so that e.g. Alt-@ sends ESC @ also on keyboards where @ is mapped to an AltGr combination.
Report mouse wheel scroll events in mouse reporting mode 1000 (note: this doesn't seem to work on all systems, assumedly due to driver interworking issues). Add mouse reporting mode 1002 to report mouse drag movement. Add mouse reporting mode 1003 to report any mouse movement. Add focus event reporting (mode 1004), compatible with xterm and mintty.
Add escape sequences for not bold (22), not invisible (28), not blinking (25) (compatible with xterm and mintty).
Support VT100 line drawing graphics mode in console window (compatible with xterm and mintty).
Handle native DOS paths always as if mounted with "posix=0,noacl".
Handle UNC paths starting with slashes identical to /cygdrive paths. In other words, use the /cygdrive mount flags for these paths as well.
Recognize NWFS filesystem and workaround broken OS call.
New support for eXtensible Data Record (XDR) encoding and decoding, as defined by RFCs 1014, 1832, and 4506. The XDR protocol and functions are useful for cross-platfrom data exchange, and are commonly used as the core data interchange format for Remote Procedure Call (RPC) and NFS.
Windows 95, 98 and Me are not supported anymore. The new Cygwin 1.7 DLL will not run on any of these systems.
Add support for Windows 7 and Windows Server 2008 R2.
Mount points are no longer stored in the registry. Use /etc/fstab and /etc/fstab.d/$USER instead. Mount points created with mount(1) are only local to the current session and disappear when the last Cygwin process in the session exits.
Cygwin creates the mount points for /, /usr/bin, and /usr/lib automatically from it's own position on the disk. They don't have to be specified in /etc/fstab.
If a filename cannot be represented in the current character set, the character will be converted to a sequence Ctrl-X + UTF-8 representation of the character. This allows to access all files, even those not having a valid representation of their filename in the current character set. To always have a valid string, use the UTF-8 charset by setting the environment variable $LANG, $LC_ALL, or $LC_CTYPE to a valid POSIX value, such as "en_US.UTF-8".
PATH_MAX is now 4096. Internally, path names can be as long as the underlying OS can handle (32K).
struct dirent now supports d_type, filled out with DT_REG or DT_DIR. All other file types return as DT_UNKNOWN for performance reasons.
The CYGWIN environment variable options "ntsec" and "smbntsec" have been replaced by the per-mount option "acl"/"noacl".
The CYGWIN environment variable option "ntea" has been removed without substitute.
The CYGWIN environment variable option "check_case" has been removed in favor of real case-sensitivity on file systems supporting it.
Creating filenames with special DOS characters '"', '*', ':', '<', '>', '|' is supported.
Creating files with special DOS device filename components ("aux", "nul", "prn") is supported.
File names are case sensitive if the OS and the underlying file system supports it. Works on NTFS and NFS. Does not work on FAT and Samba shares. Requires to change a registry key (see the User's Guide). Can be switched off on a per-mount basis.
Due to the above changes, managed mounts have been removed.
Incoming DOS paths are always handled case-insensitive and get no POSIX permission, as if they are mounted with noacl,posix=0 mount flags.
unlink(2) and rmdir(2) try very hard to remove files/directories even if they are currently accessed or locked. This is done by utilizing the hidden recycle bin directories and marking the files for deletion.
rename(2) rewritten to be more POSIX conformant.
access(2) now performs checks using the real user ID, as required by POSIX; the old behavior of querying based on effective user ID is available through the new faccessat(2) and euidaccess(2) APIs.
Add st_birthtim member to struct stat.
File locking is now advisory, not mandatory anymore. The fcntl(2) and the new lockf(2) APIs create and maintain locks with POSIX semantics, the flock(2) API creates and maintains locks with BSD semantics. POSIX and BSD locks are independent of each other.
Implement atomic O_APPEND mode.
New open(2) flags O_DIRECTORY, O_EXEC and O_SEARCH.
Make the "plain file with SYSTEM attribute set" style symlink default again when creating symlinks. Only create Windows shortcut style symlinks if CYGWIN=winsymlinks is set in the environment.
Symlinks now use UTF-16 encoding for the target filename for better internationalization support. Cygwin 1.7 can read all old style symlinks, but the new style is not compatible with older Cygwin releases.
Handle NTFS native symlinks available since Vista/2008 as symlinks (but don't create Vista/2008 symlinks due to unfortunate OS restrictions).
Recognize NFS shares and handle them using native mechanisms. Recognize and create real symlinks on NFS shares. Get correct stat(2) information and set real mode bits on open(2), mkdir(2) and chmod(2).
Recognize MVFS and workaround problems manipulating metadata and handling DOS attributes.
Recognize Netapp DataOnTap drives and fix inode number handling.
Recognize Samba version beginning with Samba 3.0.28a using the new extended version information negotiated with the Samba developers.
Stop faking hardlinks by copying the file on filesystems which don't support hardlinks natively (FAT, FAT32, etc.). Just return an error instead, just like Linux.
List servers of all accessible domains and workgroups in // instead of just the servers in the own domain/workgroup.
Support Linux-like extended attributes ([fl]getxattr, [fl]listxattr, [fl]setxattr, [fl]removexattr).
New file conversion API for conversion from Win32 to POSIX path and vice versa (cygwin_conv_path, cygwin_create_path, cygwin_conv_path_list).
New openat family of functions: openat, faccessat, fchmodat, fchownat, fstatat, futimesat, linkat, mkdirat, mkfifoat, mknodat, readlinkat, renameat, symlinkat, unlinkat.
Other new APIs: posix_fadvise, posix_fallocate, funopen, fopencookie, open_memstream, open_wmemstream, fmemopen, fdopendir, fpurge, mkstemps, eaccess, euidaccess, canonicalize_file_name, fexecve, execvpe.
New implementation for blocking sockets and select on sockets which is supposed to allow POSIX-compatible sharing of sockets between threads and processes.
send/sendto/sendmsg now send data in 64K chunks to circumvent an internal buffer problem in WinSock (KB 201213).
New send/recv option MSG_DONTWAIT.
IPv6 support. New APIs getaddrinfo, getnameinfo, freeaddrinfo, gai_strerror, in6addr_any, in6addr_loopback. On IPv6-less systems, replacement functions are available for IPv4. On systems with IPv6 enabled, the underlying WinSock functions are used. While I tried hard to get the functionality as POSIXy as possible, keep in mind that a *fully* conformant implementation of getaddrinfo and other stuff is only available starting with Windows Vista/2008.
Resolver functions (res_init, res_query, res_search, res_querydomain, res_mkquery, res_send, dn_comp, dn_expand) are now part of Cygwin. Applications don't have to link against minires anymore. Actually, this *is* the former libminires.a.
rcmd is now implemented inside of Cygwin, instead of calling the WinSock function. This allows rsh(1) usage on Vista/2008 and later, which dropped this function from WinSock.
Define multicast structures in netinet/in.h. Note that fully conformant multicast support is only available beginning with Vista/2008.
Improve get_ifconf. Redefine struct ifreq and subsequent datastructures to be able to keep more information. Support SIOCGIFINDEX, SIOCGIFDSTADDR and the Cygwin specific SIOCGIFFRNDLYNAM. Support real interface flags on systems supporting them.
Other new APIs: bindresvport, bindresvport_sa, gethostbyname2, iruserok_sa, rcmd_af, rresvport_af. getifaddrs, freeifaddrs, if_nametoindex, if_indextoname, if_nameindex, if_freenameindex.
Reworked pipe implementation which uses overlapped IO to create more reliable interruptible pipes and fifos.
The CYGWIN environment variable option "binmode" has been removed.
Improved fifo handling by using native Windows named pipes.
Detect when a stdin/stdout which looks like a pipe is really a tty. Among other things, this allows a debugged application to recognize that it is using the same tty as the debugger.
Support UTF-8 in console window.
In the console window the backspace key now emits DEL (0x7f) instead of BS (0x08), Alt-Backspace emits ESC-DEL (0x1b,0x7f) instead of DEL (0x7f), same as the Linux console and xterm. Control-Space now emits an ASCII NUL (0x0) character.
Support up to 64 serial interfaces using /dev/ttyS0 - /dev/ttyS63.
Support up to 128 raw disk drives /dev/sda - /dev/sddx.
New API: cfmakeraw, get_avphys_pages, get_nprocs, get_nprocs_conf, get_phys_pages, posix_openpt.
A lot of character sets are supported now via a call to setlocale(). The setting of the environment variables $LANG, $LC_ALL or $LC_CTYPE will be used. For instance, setting $LANG to "de_DE.ISO-8859-15" before starting a Cygwin session will use the ISO-8859-15 character set in the entire session. The default locale in the absence of one of the aforementioned environment variables is "C.UTF-8".
The full list of supported character sets: "ASCII", "ISO-8859-x" with x in 1-16, except 12, "UTF-8", Windows codepages "CPxxx", with xxx in (437, 720, 737, 775, 850, 852, 855, 857, 858, 862, 866, 874, 1125, 1250, 1251, 1252, 1253, 1254, 1255, 1256, 1257, 1258), "KOI8-R", "KOI8-U", "SJIS", "GBK", "eucJP", "eucKR", and "Big5".
Allow multiple concurrent read locks per thread for pthread_rwlock_t.
Implement pthread_kill(thread, 0) as per POSIX.
New API for POSIX IPC: Named semaphores: sem_open, sem_close, sem_unlink. Message queues: mq_open, mq_getattr, mq_setattr, mq_notify, mq_send, mq_timedsend, mq_receive, mq_timedreceive, mq_close, mq_unlink. Shared memory: shm_open, shm_unlink.
Only declare expected functions in <strings.h>, don't include <string.h> from here.
Support for WCONTINUED, WIFCONTINUED() added to waitpid and wait4.
New APIs: _Exit, confstr, insque, remque, sys_sigabbrev, posix_madvise, posix_memalign, reallocf, exp10, exp10f, pow10, pow10f, lrint, lrintf, rint, rintf, llrint, llrintf, llrintl, lrintl, rintl, mbsnrtowcs, strcasestr, stpcpy, stpncpy, wcpcpy, wcpncpy, wcsnlen, wcsnrtombs, wcsftime, wcstod, wcstof, wcstoimax, wcstok, wcstol, wcstoll, wcstoul, wcstoull, wcstoumax, wcsxfrm, wcscasecmp, wcsncasecmp, fgetwc, fgetws, fputwc, fputws, fwide, getwc, getwchar, putwc, putwchar, ungetwc, asnprintf, dprintf, vasnprintf, vdprintf, wprintf, fwprintf, swprintf, vwprintf, vfwprintf, vswprintf, wscanf, fwscanf, swscanf, vwscanf, vfwscanf, vswscanf.
Getting a domain user's groups is hopefully more bulletproof now.
Cygwin now comes with a real LSA authentication package. This must be manually installed by a privileged user using the /bin/cyglsa-config script. The advantages and disadvantages are noted in http://cygwin.com/ml/cygwin-developers/2006-11/msg00000.html
Cygwin now allows storage and use of user passwords in a hidden area of the registry. This is tried first when Cygwin is called by privileged processes to switch the user context. This allows, for instance, ssh public key sessions with full network credentials to access shares on other machines.
New options have been added to the mkpasswd and mkgroup tools to ease use in multi-machine and multi-domain environments. The existing options have a slightly changed behaviour.
New ldd utility, similar to Linux.
New link libraries libdl.a, libresolv.a, librt.a.
Fallout from the long path names: If the current working directory is longer than 260 bytes, or if the current working directory is a virtual path (like /proc, /cygdrive, //server), don't call native Win32 programs since they don't understand these paths.
On the first usage of a DOS path (C:\foo, \\foo\bar), the Cygwin DLL emits a scary warning that DOS paths shouldn't be used. This warning may be disabled via the new CYGWIN=nodosfilewarning setting.
The CYGWIN environment variable option "server" has been removed. Cygwin automatically uses cygserver if it's available.
Allow environment of arbitrary size instead of a maximum of 32K.
Don't force uppercase environment when started from a non-Cygwin process. Except for certain Windows and POSIX variables which are always uppercased, preserve environment case. Switch back to old behaviour with the new CYGWIN=upcaseenv setting.
Detect and report a missing DLL on process startup.
Add /proc/registry32 and /proc/registry64 paths to access 32 bit and 64 bit registry on 64 bit systems.
Add the ability to distinguish registry keys and registry values with the same name in the same registry subtree. The key is called "foo" and the value will be called "foo%val" in this case.
Align /proc/cpuinfo more closly to Linux content.
Add /proc/$PID/mounts entries and a symlink /proc/mounts pointing to /proc/self/mounts as on Linux.
Optimized strstr and memmem implementation.
Remove backwards compatibility with old signal masks. (Some *very* old programs which use signal masks may no longer work correctly).
Cygwin now exports wrapper functions for libstdc++ operators new and delete, to support the toolchain in implementing full C++ standards conformance when working with shared libraries.
Different Cygwin installations in different paths can be run in parallel without knowing of each other. The path of the Cygwin DLL used in a process is a key used when creating IPC objects. So different Cygwin DLLs are running in different namespaces.
Each Cygwin DLL stores its path and installation key in the registry. This allows troubleshooting of problems which could be a result of having multiple concurrent Cygwin installations.