These cleanup operations are not needed because they are already performed
after an optimized command substitution (whether there was an error or not).
Although using -i with -c does not seem very useful, it seems inappropriate
to read commands from the terminal in this case.
Side effect: if the -s -c extension is used and the -s option is turned off
using 'set +s' during the interactive part, the shell now exits after an
error or interrupt. Note that POSIX only specifies -s as option to sh, not
to set.
See also Austin Group issue #718.
This is required by POSIX, at least for pids that are not known child
processes.
Other problems with job specifications still cause wait to abort with
exit status 2.
PR: 176916
This is only part of the PR; the behaviour for unknown/invalid pids/jobs
remains unchanged (aborts the builtin with status 2).
PR: 176916
Submitted by: Vadim Goncharov
This reverts commit r247274.
As maintainer of sh, I disapprove of this feature addition.
It is too specific and can be done without easily using find(1) or stat(1).
I will add some hints to the test(1) man page shortly.
In general, FreeBSD sh is not the place to invent new shell language
features. This is how it has been maintained and adding features randomly
does not work with that.
The new syntax (e.g. [ FILE1 -ntca FILE2 ]) looks cryptic to me.
* Work around kernel bugs that cause a spurious [EINTR] return if a
debugger (such as truss(1)) is attached.
* Write an error message if an error other than [EINTR] occurs.
PR: bin/178664
The linked list of stack marks may cause problems if the allocation stack is
used between an exception and a higher-level popstackmark(), as it may then
touch a stack mark that is local to a function which has returned.
Also, the adjustment compares to a pointer passed to realloc(), which is
undefined behaviour.
Instead of adjusting stack marks when reallocating stack blocks, ensure that
such an adjustment is never necessary by fixing a small piece of memory in
place at a stack mark. This also simplifies the code.
To avoid the problems reported in bin/175922, it remains necessary to call
setstackmark() after popstackmark() if the stack mark remains in use.
* If read -t times out, return status as if interrupted by SIGALRM
(formerly 1).
* If a trapped signal interrupts read, return status 128+sig (formerly 1).
* If [EINTR] occurs but there is no trap, retry the read (for example
because of a SIGWINCH in interactive mode).
* If a read error occurs, write an error message and return status 2.
As before, a variable assignment error returns 2 and discards the remaining
data read.
the free(3) of mntbuf ... again. There's no point in doing
useless extra work when we're about to exit.
See also r240565.
Not reading file history: uqs
If the bs= expr operand is specified and no conversions other than sync,
noerror, or notrunc are requested, the data returned from each input
block shall be written as a separate output block.
In particular, when both bs=size and conv=sparce were specified, the
resulted file was fully filled, instead of sparce.
PR: standards/177742
Submitted by: Matthew Rezny <mrezny@hexaneinc.com>
MFC after: 2 weeks
- Add an empty line in usage() according to style(9)
PR: bin/177076
Submitted by: Fernando <fernando.apesteguia@gmail.com>
Approved by: cperciva (mentor)
While here:
- use NULL in the context of pointers
- use memset instead of bzero throughout the file
- free memory to appease clang static analyzer
Found by: Coverity Scan (the UNINIT one)
This allows mapping a tape drive in a changer (as reported by
'chio status') to a sa(4) driver instance by comparing the
serial numbers.
The designators can be ASCII (which is printed out directly), binary
(which is printed in hex format) or UTF-8, which is printed in either
native UTF-8 format if the terminal can support it, or in %XX notation
for non-ASCII characters. Thanks to Hiroki Sato <hrs@> for the
explaining UTF-8 printing and example UTF-8 printing code.
chio.h: Modify the changer_element_status structure to add new
fields and definitions from the SMC3r16 spec.
Rename the original CHIOGSTATUS ioctl to OCHIOGTATUS and
define a new CHIOGSTATUS ioctl.
Clean up some tab/space issues.
chio.c: For the 'status' subcommand, print the designator field
if it is supplied by a device.
scsi_ch.h: Add new flags for DVCID and CURDATA to the READ
ELEMENT STATUS command structure.
Add a read_element_status_device_id structure
for the data fields in the new standard. Add new
unions, dt_or_obsolete and voltage_devid, to hold
and address data from either SCSI-2 or newer devices.
scsi_ch.c: Implement support for fetching device IDs with READ
ELEMENT STATUS data.
Add new arguments to scsi_read_element_status() to
allow the user to request the DVCID and CURDATA bits.
This isn't compiled into libcam (it's only an internal
kernel interface), so we don't need any special
handling for the API change.
If the user issues the new CHIOGSTATUS ioctl, copy all of
the available element status data out. If he issues the
OCHIOGSTATUS ioctl, we don't copy the new fields in the
structure.
Fix a bug in chopen() that would result in the peripheral
never getting unheld if chgetparams() failed.
Sponsored by: Spectra Logic
Submitted by: Po-Li Soong
MFC After: 1 week
This compiler flag enforces that that people either mark variables
static or use an external declarations for the variable, similar to how
-Wmissing-prototypes works for functions.
Due to the fact that Yacc/Lex generate code that cannot trivially be
changed to not warn because of this (lots of yy* variables), add a
NO_WMISSING_VARIABLE_DECLARATIONS that can be used to turn off this
specific compiler warning.
Announced on: toolchain@
Introduce an explicit close of the output descriptor so that work done
on close is accounted for in the summary output triggered at exit
(implicit close()s occur after atexit() hooks).
This is useful because some devices such as cfi(4) may perform
signficant work after a close occurs (e.g. erasing and rewriting a
block of flash).
Use non-blocking I/O to write as much as the pipe will accept (often 64K,
but it can be as little as 4K), avoiding the need for the ugly PIPESIZE
constant. If PIPESIZE was set too high, a deadlock would occur.
It now passes WARNS=7 with clang on i386.
GCC 4.2.1 does not understand setjmp() properly so will always trigger
-Wuninitialized. I will not add the volatile keywords to suppress this.
In some other shells, things like $((a);(b)) are command substitutions.
Also, there are shells that have an extension ((ARITH)) that evaluates an
arithmetic expression and returns status 1 if the result is zero, 0
otherwise. This extension may lead to ambiguity with two subshells starting
in sequence.
u_long. Before this change it was of type int for syscalls, but prototypes
in sys/stat.h and documentation for chflags(2) and fchflags(2) (but not
for lchflags(2)) stated that it was u_long. Now some related functions
use u_long type for flags (strtofflags(3), fflagstostr(3)).
- Make path argument of type 'const char *' for consistency.
Discussed on: arch
Sponsored by: The FreeBSD Foundation
If syntactically invalid job identifiers are to be taken as jobs that exited
with status 127, this should not apply to options, so that we can add
options later if need be.
This ensures 'return' in a trap returns the correct status to the caller.
If evalskip is not set or if it is overridden by a previous evalskip, keep
the old behaviour of restoring the exit status from before the trap.
access, birth, change and modify times of two files, instead of only
being able to compare modify times. The builtin test in sh(1) will
automagically acquire the same expansion.
Approved by: grog
MFC after: 2 weeks
If a stack mark is set while the current stack block is empty, the stack
block may move later on (because of realloc()) and the stack mark needs to
be updated. This updating does not happen after popstackmark() has been
called; therefore, call setstackmark() again if the stack mark is still
being used.
For some reason, this only affects a few users. I cannot reproduce it. The
situation seems quite rare as well because an empty stack block would
usually be freed (by popstackmark()) before execution reaches a
setstackmark() call.
PR: 175922
Tested by: KT Sin
Now it outputs fixed files, which use constants provided by the C standard
library to determine appropriate values for the target machine.
Before, mksyntax inspected the host machine which resulted in subtle
breakage if e.g. char is signed on the host and unsigned on the target such
as when cross-compiling on x86 for ARM.
Tested using -funsigned-char on amd64. Compiling build-tools without it and
sh itself with it causes various tests to fail without this change but not
with this change. With consistent -funsigned-char, tests pass with or
without this change.
The mksyntax program could be removed and syntax.c and syntax.h committed to
the repository.
Submitted by: Christoph Mallon
MFC after: 2 weeks
ISO/IEC 9899:1999 (E) 5.2.1p3 guarantees that the values of the characters
0123456789 are contiguous.
The generated syntax.c and syntax.h remain the same.
Submitted by: Christoph Mallon
Expand here documents at the same point other redirections are expanded but
use a non-fork subshell environment (like simple command substitutions) for
compatibility. Substitition errors result in an empty here document like
before.
As a result, a fork is avoided for short (<4K) expanded here documents.
Unexpanded here documents (with quoted end marker after <<) are not affected
by this change. They already only forked when >4K.
Side effects:
* Order of expansion is slightly different.
* Slow expansions are not executed in parallel with the redirected command.
* A non-fork subshell environment is subtly different from a forked process.
set an exclusive advisory lock on stdout. This will be used to guarantee
orderly writing to METALOG.
Sponsored by: DARPA, AFRL
Obtained from: NetBSD (mason)
Otherwise with '-v' we print out the file name as if it was copied:
/tmp/2gb-card/M0132.CTG not overwritten
/mnt/DCIM/CANONMSC/M0132.CTG -> /tmp/2gb-card/M0132.CTG
If a loop contained certain commands (such as redirected compound commands),
the temporary memory for the redirection was not freed between iterations of
the loop but only after the loop.
Put a stackmark in evaltree(), freeing memory whenever a node has been
evaluated. Some other stackmarks are then redundant; remove them.
Example:
while :; do { :; } </dev/null; done
command name of a thread from a multi-threaded process that doesn't have
an available argument list (such as kernel processes) and threads display
is enabled via -H.
Reviewed by: alfred, delphij, eric@vangyzen.net
MFC after: 1 week
Instead of rechecking relative paths for all hashed utilities after a cd,
track if any utility in cmdtable depends on a relative path in PATH.
If there is such a utility, cd clears the entire table.
As a result, the '*' in hash no longer happens.
Accessing sys_siglist directly requires rtld to copy it from libc to the sh
executable's BSS. Also, strsignal() will put in the signal number for
unknown signals (FreeBSD-specific) so we need not do that ourselves.
Unfortunately, there is no function for sys_signame.
If there is a write error on stdout, a message will be printed (to stderr)
and the exit status will be changed to 2 if it would have been 0 or 1.
PR: bin/158206
if (exists AND (NOT f_option) AND
((not_writable AND input_is_terminal) OR i_option))
prompt
in particular, add the test for input_is_terminal
PR: bin/173039
Submitted by: Mark Johnston <markjdb@gmail.com>
Approved by: cperciva
MFC after: 3 days
* The last character is not displayed.
* If the alias ends with itself (as a word), an infinite memory-eating loop
occurs.
If an alias is defined initially, a space is appended to avoid recursion but
this did not happen when an alias was later modified.
PR: bin/173418
Submitted by: Daniel F.
MFC after: 1 week
sorting order for time and name with the -t option. IEEE Std 1003.2
(POSIX.2) mandates that the -t option sort in descending order, and
that if two files have the same timestamp, they should be sorted in
ascending order of their names. The -r flag reverses both of these
sort orders, so they're never the same. This creates significant
problems for sequentially named files stored on FAT file systems,
where it can be impossible to list them in the order in which they
were created.
Add , (comma) option to print file sizes grouped and separated by
thousands using the non-monetary separator returned by localeconv(3),
typically a comma or period.
MFC after: 14 days
Although sufficient memory is available for a longer string in cmdname,
this is undefined behaviour anyway.
Side effect: for alignment reasons, an additional byte of memory is
allocated per hashed command.
In addition to adding missing `static' keywords:
- bin/dd: Pull in `extern.h' to guarantee consistency with source file.
- libexec/rpc.rusersd: Move shared globals into an extern.h.
- libexec/talkd: Move `debug' and `hostname' into extern.h.
- usr.bin/cksum: Put counters in extern.h, as they are used by ckdist/mtree.
- usr.bin/m4: Move `end_result' into extern.h.
- usr.sbin/services_mkdb: Move shared globals into an extern.h.
In addition to adding `static' where possible:
- bin/date: Move `retval' into extern.h to make it visible to date.c.
- bin/ed: Move globally used variables into ed.h.
- sbin/camcontrol: Move `verbose' into camcontrol.h and fix shadow warnings.
- usr.bin/calendar: Remove unneeded variables.
- usr.bin/chat: Make `line' local instead of global.
- usr.bin/elfdump: Comment out unneeded function.
- usr.bin/rlogin: Use _Noreturn instead of __dead2.
- usr.bin/tset: Pull `Ospeed' into extern.h.
- usr.sbin/mfiutil: Put global variables in mfiutil.h.
- usr.sbin/pkg: Remove unused `os_corres'.
- usr.sbin/quotaon, usr.sbin/repquota: Remove unused `qfname'.
This self-written compiler warning, which is hopefully going to be
committed into LLVM sources soon, warns about potentially missing
`static' keywords, similar to -Wmissing-prototypes.
- bin/pax: Move external declaration of chdname and s_mask into extern.h.
- bin/setfacl: Move setfacl.c-specific stuff out of setfacl.h.
- sbin/mount_fusefs: Remove char *progname; use getprogname().
- others: add `static' where possible.
This reduces code duplication and code size.
/usr/bin/printf is not affected.
Side effect: different error messages when certain builtins are passed
invalid options.
help tools understand that we're not leaking it.
PR: bin/171634
Submitted by: Erik Cederstrand <erik@cederstrand.dk>
Approved by: cperciva
MFC after: 3 days
# setfacl -m u:trasz:rwx x
# setfacl -m u:root:rwx x
# getfacl x
# file: x
# owner: root
# group: wheel
user::rw-
user:root:rwx
user:trasz:rwx
group::r--
mask::rwx
other::r--
# setfacl -m u:root:rwx x
setfacl: x: acl_calc_mask() failed: Invalid argument
setfacl: x: failed to set ACL mask
For NFSv4 ACLs, this sort of situation would result in duplicated
entries.
MFC after: 1 month
PR submitter suggested adding it to acl(3) instead, but I don't think
pointing ordinary users at section 3 is a good idea.
PR: docs/162380
MFC after: 1 month
This structure is not part of POSIX. According to POSIX, gettimeofday()
has the following prototype:
int gettimeofday(struct timeval *restrict tp, void *restrict tzp);
Also, POSIX states that gettimeofday() shall return 0 (as long as tzp is
not used). Remove dead error handling code. Also use NULL for a
nul-pointer instead of integer 0.
While there, change all pieces of code that only use tv_sec to use
time(3), as this provides less overhead.
symbolic link to a directory for the target as a symbolic link instead of
a directory. This makes it possible to atomically update a symbolic
link using rename().
Reviewed by: gj
MFC after: 2 weeks
When waiting for child processes using "wait" or if "set -T" is in effect, a
signal interrupts the wait. Make sure there is no window where the signal
handler may be invoked (setting a flag) just before going to sleep.
There is a similar race condition in the shell language, but scripts can
avoid it by exiting from the trap handler or enforcing synchronization using
a fifo.
If SIGCHLD is not trapped, a signal handler must be installed for it. Only
install this handler for the duration of the wait to avoid triggering
unexpected [EINTR] errors elsewhere.
Note that for some reason only SIGINT and SIGQUIT interrupt a "wait"
command. This remains the case.
Examples:
export x=~
now expands the tilde
local y=$1
is now safe, even if $1 contains IFS characters or metacharacters.
For a word to "look like an assignment", it must start with a name followed
by an equals sign, none of which may be quoted.
The special treatment applies when the first word (potentially after
"command") is "export", "readonly" or "local". There may be quoting
characters but no expansions. If "local" is overridden with a function there
is no special treatment ("export" and "readonly" cannot be overridden with a
function).
If things like
local arr=(1 2 3)
are ever allowed in the future, they cannot call a "local" function. This
would either be a run-time error or it would call the builtin.
This matches Austin Group bug #351, planned for the next issue of POSIX.1.
PR: bin/166771
On recent versions of NetBSD's libedit, el_gets
now sets el_len to -1 on error so we can
distinguish between a NULL string and an error.
This fixes sh from exiting with newer versions
of libedit now allowing EINTR to return.
Obtained from: NetBSD
Reviewed by: jilles
MFC after: 3 weeks
directory entry then use the struct stat from that instead of doing
it again, and skip the rm_overwrite() call if fts_read() indicated
that the entry couldn't be a regular file.
Obtained from: OpenBSD
MFC after: 1 week
that the file we have opened is the one we expected. Also open in
non-blocking mode to avoid a potential hang with FIFOs.
Obtained from: NetBSD via OpenBSD
1. Avoid a cd back into ${.CURDIR} to run mkbuiltins when we know make
will first cd into ${.OBJDIR}. Keep the cwd to what make sets it to.
2. Don't tell mkbuiltins where to write to (= ${.OBJDIR}), but where to
get sources from (= ${.CURDIR}). This to compensate for point 1.
This fixes a problem with bmake's mk files that optimize ${.OBJDIR} to
expand to "." after changing cwd, not taking into account that the
target is pretty much undoing that and not getting the full path to the
object tree anymore.
scripts the way sysctl(8) is. The -N option, like in sysctl(8),
displays only the kenv names, not their values. The -v option prints an
individual kenv variable name with its value as name="value". This is
the inverse of sysctl(8)'s -n flag, since the default behaviour of
kenv(1) is already like sysctl(8) -n.
Submitted by: Garrett Cooper < yanegomi AT gmail DOT com >
MFC after: 1 week
quotation. Also make sure we have the same amount of columns in each row as
the number of columns we specify in the head arguments.
Reviewed by: brueffer
This uses vfork() for simple commands and command substitutions containing a
single simple command, invoking an external program under certain conditions
(no redirections or variable assignments, non-interactive shell, no job
control). These restrictions limit the amount of code executed in a vforked
child.
There is a large speedup (for example 35%) in microbenchmarks. The
difference in buildkernel is smaller (for example 0.5%) but still
statistically significant. See
http://lists.freebsd.org/pipermail/freebsd-hackers/2012-January/037581.html
for some numbers.
The use of vfork() can be disabled by setting a variable named
SH_DISABLE_VFORK.
In the first command of a 'for', $? should be the exit status of the last
pipeline (command substitution in the word list or command before 'for'),
not always 0.
Before this fix, only the first statement of the trap was executed if
evalskip was set. This is for example the case when:
o "-e" is set for this shell
o a trap is set on EXIT
o a function returns 1 and causes the script to abort
Reviewed by: jilles
MFC after: 2 weeks
Also, rework evalcase() to not evaluate any tree. Instead, return the
NCLISTFALLTHRU node and handle it in evaltree().
Fixed bugs:
* If a ;& list with non-zero exit status is followed by an empty ;; or final
list, the exit status of the case command should be equal to the exit
status of the ;& list, not 0.
* An empty ;& case should not reset $?.
* If no pattern is matched, POSIX says the exit status shall be 0 (even if
there are command substitutions).
* If a pattern is matched and there are no command substitutions, the first
command should see the $? from before the case command, not always 0.
The errno message display added in r222292 did not take attempting to
cd to a non-directory or something that cannot be stat()ed into account.
PR: bin/164070
MFC after: 10 days
This improves performance for globs where a slash or another component
follows a component with metacharacters by eliminating unnecessary attempts
to open directories that are not.
This is not necessary: errors are already caught in evalbackcmd() and
forcelocal handles changes to variables.
Note that this depends on r223024.
MFC after: 4 weeks
Free expanded case text before executing commands.
Remove impossible evalskip checks (expanding an argument cannot set
evalskip anymore since $(break) and the like are properly executed in a
subshell environment).
For these simple utilities, it doesn't harm to make all global variables
static. In fact, this allows the compiler to perform better forms of
optimisation and analysis.
display() to calculate column widths, but was not initialized in
main(). This resulted in a division by zero.
Noticed by: Michael Butler <imb@protected-networks.net>
- In the argc == 0 case, just populate the mount list as before, but
do not calculate widths, update totals or print anything.
- In the argv > 0 case, collect information about the requested file
systems and store it in the mount list, but do not calculate
widths, update totals or print anything.
- In either case, once all the information has been collected,
iterate once through the mount list to calculate widths and totals,
then once more to print everything.
This also fixes two bugs: firstly, column widths were not calculated
correctly if more than one file system was specified on the command
line; and secondly, file systems with MNT_IGNORE were included in the
totals even if -a was not specified.
Noticed by: Paul Schenkeveld
MFC after: 3 weeks
- there's no reason the semantics of the -x flag are being explained in
the -a flag description
- be more precise regarding the relation between the -a flag and the
security.bsd.see_other_uids sysctl
- describe the format of the -t flag's argument
- 'con' no longer is a possible entry in the 'TT' column
- explain that the 'TT' column refers to pseudo-terminals via mere numbers
- add a hint in the 'tt' keyword description that a keyword 'tty' exists,
which will give the full terminal pathname
Submitted by: arundel (via docs@) (original)
MFC after: 1 week
With-MFC: 225908
As of FreeBSD 6, devices can only be opened through devfs. These device
nodes don't have major and minor numbers anymore. The st_rdev field in
struct stat is simply based a copy of st_ino.
Simply display device numbers as hexadecimal, using "%#jx". This is
allowed by POSIX, since it explicitly states things like the following
(example taken from ls(1)):
"If the file is a character special or block special file, the
size of the file may be replaced with implementation-defined
information associated with the device in question."
This makes the output of these commands more compact. For example, ls(1)
now uses approximately four columns less. While there, simplify the
column length calculation from ls(1) by calling snprintf() with a NULL
buffer.
Don't be afraid; if needed one can still obtain individual major/minor
numbers using stat(1).
Because sh executes commands in subshell environments without forking in
more and more cases (particularly from 8.0 on), it makes sense to describe
subshell environments more precisely using ideas from POSIX, together with
some FreeBSD-specific items.
In particular, the hash and times builtins may not behave as if their state
is copied for a subshell environment while leaving the parent shell
environment unchanged.
to re-establishment of 64bit arithmetic, but is committed separately, to
not obscure that conversion. This commit does not change the observed
behaviour of expr in any way. Style will be fixed in a follow-up commit.
again. This brings back the behaviour of expr in FreeBSD-4, which had been
reverted due to an assumed incompatbility with POSIX.1 for FreeBSD-5.
This issue has been discussed in the freebsd-standards list, and the
consensus was, that POSIX.1 is in fact not violated by this extension,
since it affects only cases of POSIX undefined behaviour (overflow of
signed long).
Other operating systems did upgrade their versions of expr to support
64bit range, after it had been initially brought to FreeBSD. They have
used it for a decade without problems, meanwhile.
The -e option is retained, but it will only select less strict checking
of numeric parameters (leading white-space, leading "+" are allowed and
skipped, an empty string is considered to represent 0 in numeric context.)
The call of check_utility_compat() as a means of establishing backwards
compatibility with FreeBSD-4 is considered obsolete, but preserved in
this commit. It is expected to be removed in a later revision of this
file.
Reviewed by: bde, das, jilles
MFC after: 2 month (those parts that do not violate POLA)
* Shell patterns are also for ${var#pat} and the like.
* An '!' by itself will not trigger pathname generation so do not call it a
meta-character, even though it has a special meaning directly after an
'['.
* Character ranges are locale-dependent.
* A '^' will complement a character class like '!' but is non-standard.
MFC after: 1 week
POSIX requires a -h option to sh and set, to locate and remember utilities
invoked by functions as they are defined. Given that this
locate-and-remember process is optional elsewhere, it seems safe enough to
make this option do nothing.
POSIX does not specify a long name for this option. Follow ksh in calling it
"trackall".
Replacing ;; with the new control operator ;& will cause the next list to be
executed as well without checking its pattern, continuing until a list ends
with ;; or until the end of the case statement. This is like omitting
"break" in a C "switch" statement.
The sequence ;& was formerly invalid.
This feature is proposed for the next POSIX issue in Austin Group issue
#449.
The eval special builtin now runs the code with EV_EXIT if it was run
with EV_EXIT itself.
In particular, this eliminates one fork when a command substitution contains
an eval command that ends with an external program or a subshell.
This is similar to what r220978 did for functions.
Have mkbuiltins write the prototypes for the *cmd functions to builtins.h
instead of builtins.c and include builtins.h in more .c files instead of
duplicating prototypes for *cmd functions in other headers.
In optimized command substitution, save and restore any variables changed by
expansions (${var=value} and $((var=assigned))), instead of trying to
determine if an expansion may cause such changes.
If $! is referenced in optimized command substitution, do not cause jobs to
be remembered longer.
This fixes $(jobs $!) again, simplifies the man page and shortens the code.
When I added UTF-8 support in r221646, the LC_COLLATE-based ordering broke
because of sign extension of char.
Because of libc restrictions, this does not work for UTF-8. For UTF-8
locales, ranges always use character code order.
In most cases, login shells are started from the home directory, but not in
all, such as xterm -ls.
This commit depends on r222957 for read_profile() performing parameter
expansion.
PR: bin/50569
The function name expandstr() and the general idea of doing this kind of
expansion by treating the text as a here document without end marker is from
dash.
All variants of parameter expansion and arithmetic expansion also work (the
latter is not required by POSIX but it does not take extra code and many
other shells also allow it).
Command substitution is prevented because I think it causes too much code to
be re-entered (for example creating an unbounded recursion of trace lines).
Unfortunately, our LINENO is somewhat crude, otherwise PS4='$LINENO+ ' would
be quite useful.
The "exp" builtin is undocumented, non-standard and not very useful.
If exp's return value is not used, something like
VAR=$(exp EXPRESSION)
is equivalent to
VAR=$((EXPRESSION))
except that errors in the expression are fatal and quoting special
characters is not needed in the latter case.
If exp's return value is used, something like
if exp EXPRESSION >/dev/null
can be replaced by
if [ $((EXPRESSION)) -ne 0 ]
with similar differences.
The exp-run showed that "let" is close enough to bash's and ksh's builtin
that removing it would break a few ports. Therefore, "let" remains in 9.x.
PR: bin/104432
Exp-run done by: pav (with some other sh(1) changes)
CDPATH should be ignored not only for pathnames starting with '/' but also
for pathnames whose first component is '.' or '..'.
The man page already describes this behaviour.
If IFS is null, unquoted $@/$* should still expand to separate words.
This differs from quoted $@ (which does not depend on IFS) in that pathname
generation is performed and empty words are removed.
If the length of a directory in PATH together with the given filename
exceeded FILENAME_MAX (which may happen even for pathnames that work), a
static buffer was overflown.
The static buffer is unnecessary, we can use the stalloc() stack.
Obtained from: NetBSD
MFC after: 1 week
