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: 'This script aims at recognizing all Bourne compatible shells. Emphasis is on shells without any version variables. Please comment to mascheck@in-ulm.de' : '$Id: whatshell.sh.comments.html,v 1.5 2021/02/13 00:37:50 xmascheck Exp xmascheck $' : 'fixes are tracked on www.in-ulm.de/~mascheck/various/whatshell/' LC_ALL=C; export LC_ALL : 'trivial cases first, yet parseable for historic shells' : '7th edition Bourne shell aka the V7 shell did not know # as comment sign, yet.' : 'Workaround: the argument to the : null command can be considered a comment,' : 'protect it, because the shell would have to parse it otherwise.' case $BASH_VERSION in *.*) { echo "bash $BASH_VERSION";exit;};;esac : '"exec echo" would call the external command instead of the built-in.' : 'Thus: echo and exit, in the current context with { ... }' : 'It is not defined as function until later, because Bourne shells before SVR2 do not know functions.' case $ZSH_VERSION in *.*) { echo "zsh $ZSH_VERSION";exit;};;esac case "$VERSION" in *zsh*) { echo "$VERSION";exit;};;esac : 'zsh 2.x has "$VERSION"' case "$SH_VERSION" in *PD*) { echo "$SH_VERSION";exit;};;esac case "$KSH_VERSION" in *PD*|*MIRBSD*) { echo "$KSH_VERSION";exit;};;esac case "$POSH_VERSION" in 0.[1234]|0.[1234].*) \ { echo "posh $POSH_VERSION, possibly slightly newer, yet<0.5";exit;} ;; *.*|*POSH*) { echo "posh $POSH_VERSION";exit;};; esac : 'In some posh versions something went wrong when compiling in the version' : '(a literal "POSH_VERSION" instead of the variable value)' case $YASH_VERSION in *.*) { echo "yash $YASH_VERSION";exit;};;esac : 'traditional Bourne shell' (eval ': $(:)') 2>/dev/null || { : 'Traditional Bourne shells do not implement the $( ) form of command substitution.' : 'Use eval to uncouple the failing part from the current script, and evaluate the delivered exit status.' case `(:^times) 2>&1` in *0m*):;; *)p=' (and pipe check for Bourne shell failed)';;esac : 'Almost all traditional Bourne shells implement ^ as an alias for |.' : 'Use a built-in with output to verify: times.' : 'pre-SVR2: no functions, no echo built-in.' (eval 'f(){ echo :; };f') >/dev/null 2>&1 || { : 'Bourne shells before SVR2 do not know functions. Protect the possible failure with eval (like above).' ( eval '# :' ) 2>/dev/null || { echo '7th edition Bourne shell'"$p";exit;} : '7th ed had not implemented # as comment sign, yet.' ( : ${var:=value} ) 2>/dev/null || : 'test for NULL in the parameter expansion (with the : notation) came with System III.' : 'Otherwise, it is a 7th ed shell with comments. BSD added this, and some current ports:' { echo '7th edition Bourne shell, # comments (BSD, or port)'"$p";exit;} set x x; shift 2;test "$#" != 0 && { echo 'System III Bourne shell'"$p";exit;} { echo 'SVR1 Bourne shell'"$p";exit;} : '"shift n" came with SVR1.' } }; : 'keep syntactical block small for pre-SVR2' # Since SVR2 functions are available, so the block ends as soon as all possible pre-SVR2 variants # are done. From now on we can use a function for a shorter echo+exit. myex(){ echo "$@";exit;} # "exec echo" might call the external command # Stephane Chazelas points out that the external echo is not always called: called in the Bourne # shell, ash, bash and the AT&T variants of ksh, but not in zsh, pdksh and its derivatives. (eval ': $(:)') 2>/dev/null || { (set -m; set +m) 2>/dev/null && { # SVR4 implements job control, which can be toggled with the flag "m". priv=0;(priv work)>/dev/null 2>&1 && case `(priv work)2>&1` in *built*|*found*) priv=1;;esac # SVR4.2 implements the priv built-in. work is a reliable argument. # There are pre-SVR4.2 shells, which alread accept the syntax but do not implement it. # Even the unimplemented built-in can exit with 0, thus the output has to be checked. read_r=0;(echo|read -r dummy 2>/dev/null) && read_r=1 # checking for "read -r" is an alternative. a_read=0;unset var;set -a;read var <&-;case `export` in *var*) a_read=1;;esac # Bugfix after SVR4.0: variables set with "read" are also exported. case_in=0;(eval 'case x in in) :;;esac')2>/dev/null && case_in=1 # SunOS 5 and its descendant are probably the only variants which have this bug fixed: # elsewhere the second "in" wrongly is still recognized as syntax (and thus an error) # instead as some arbitrary pattern. ux=0;a=`(notexistent_cmd) 2>&1`; case $a in *UX*) ux=1;;esac # Some other post SVR4.0 shells already implement "UX: ..." error messages # which had been defined in the SVID, the System V Interface Definition. case $priv$ux$read_r$a_read$case_in in 11110) myex 'SVR4.2 MP2 Bourne shell' ;; 11010) myex 'SVR4.2 Bourne shell' ;; 10010|01010) myex 'SVR4.x Bourne shell (between 4.0 and 4.2)' ;; 00111) myex 'SVR4 Bourne shell (SunOS 5 schily variant, before 2016-02-02)' ;; 00101) myex 'SVR4 Bourne shell (SunOS 5 heirloom variant)' ;; 00001) myex 'SVR4 Bourne shell (SunOS 5 variant)' ;; 00000) myex 'SVR4.0 Bourne shell' ;; *) myex 'unknown SVR4 Bourne shell variant' ;;esac } # It was not a SVR4 shell. For SVR3 check two features, # whether "read" without arguments yields an error (the safe check) # and whether "getopts" is implemented. This is the more important change, # but there are OSR variants where it was removed. r=0; case `(read) 2>&1` in *"missing arguments"*) r=1;;esac g=0; (set -- -x; getopts x var) 2>/dev/null && g=1 case $r$g in 11) myex 'SVR3 Bourne shell' ;; 10) myex 'SVR3 Bourne shell (but getopts built-in is missing)' ;; 01) myex 'SVR3 Bourne shell (but read built-in does not match)' ;; 00) (builtin :) >/dev/null 2>&1 && myex '8th edition (SVR2) Bourne shell'"$p" # No SVR3, thus SVR2 - or 8th edition. The latter comes with "builtin" instead of "type". (type :) >/dev/null 2>&1 && myex 'SVR2 Bourne shell'"$p" || myex 'SVR2 shell (but type built-in is missing)'"$p" # I do not know any Bourne shell without "type" built-in, but if there is one it will be caught here. ;;esac } # Schily sh since 2016-02-02 is the only traditional-like variant which implements $(). # So try another simple feature which is only implemented in traditional Bourne shells. # Test this separately, because there's also a variant which doesn't implement ^. # Since 2016-05-24 the shell is even posix like and thus implements $(( )) case $( (:^times) 2>&1) in *0m*) case `eval '(echo $((1+1))) 2>/dev/null'` in 2) myex 'SVR4 Bourne shell (SunOS 5 schily variant, posix-like, since 2016-05-24)' ;;*) myex 'SVR4 Bourne shell (SunOS 5 schily variant, since 2016-02-02, before 2016-05-24)' ;;esac ;;esac # Since 2016-08-08, when running in posix mode (called with "-o posix", or compiled to posix mode), # it even doesn't accept ^ as |. But it implements type -F. type -F >/dev/null 2>&1 && myex 'SVR4 Bourne shell (SunOS 5 schily variant, since 2016-08-08, in posix mode)' # Almquist shell aka ash (typeset -i var) 2>/dev/null || { # typeset is Korn shell specific. If it is not implemented it must be an Almquist shell. # There is a better check for Almquist shells ("%func" as suffix in PATH component), but it requires file system access. case $SHELLVERS in "ash 0.2") myex 'original ash';;esac # Only the original shell had a version variable. test "$1" = "debug" && debug=1 # Safe the argument to this script before we are fiddling with the positional parameters. n=1; case `(! :) 2>&1` in *not*) n=0;;esac # negation came with 4.4 BSD Alpha b=1; case `echo \`:\` ` in '`:`') b=0;;esac # nesting of `...` was possible with 4.4 BSD and with the 386BSD 0.2.4 patchkit, # which was also used by NetBSD 0.9 and Minix. # Minix has a bugfix about getopt concerning OPTIND: g=0; { set -- -x; getopts x: var case $OPTIND in 2) g=1;;esac;} >/dev/null 2>&1 # OPTIND is set correctly if getopt yields an error if an argument to an option is missing. # Some busybox sh might not have getopts available, so even redirect errors from the block. # FreeBSD 11 had a getopts fix. p=0; (eval ': ${var#value}') 2>/dev/null && p=1 # The # and % form of parameter expansion is implemented in 4.4 BSD Lite2 # and thus BSD/OS 3.x, but also since NetBSD 1.2. r=0; ( (read</dev/null)) 2>/dev/null; case $? in 0|1|2) var=`(read</dev/null)2>&1`; case $var in *arg*) r=1;;esac ;;esac # read without arguments yields an error message since 4.4 BSD lite. # Some ash segfault upon this, so check for a clean exit status in advance. v=1; set x; case $10 in x0) v=0;;esac # NetBSD 1.3 and its descendants handle $10 as ${10} instead of ${1}0 t=0; (PATH=;type :) >/dev/null 2>&1 && t=1 # The original ash (accidentally?) had not implemented the "type" built-in. # Early Net- and FreeBSD added it. test -z "$debug" || echo debug '$n$b$g$p$r$v$t: ' $n$b$g$p$r$v$t case $n$b$g$p$r$v$t in 00*) myex 'early ash (4.3BSD, 386BSD 0.0-p0.2.3/NetBSD 0.8)' ;; 010*) myex 'early ash (ash-0.2 port, Slackware 2.1-8.0,'\ '386BSD p0.2.4, NetBSD 0.9)' ;; 1110100) myex 'early ash (Minix 2.x-3.1.2)' ;; 1000000) myex 'early ash (4.4BSD Alpha)' ;; 1100000) myex 'early ash (4.4BSD)' ;; 11001*) myex 'early ash (4.4BSD Lite, early NetBSD 1.x, BSD/OS 2.x)' ;; 1101100) myex 'early ash (4.4BSD Lite2, BSD/OS 3 ff)' ;; 1101101) myex 'ash (FreeBSD -10.x, Cygwin pre-1.7, Minix 3.1.3 ff)' ;; 1111101) myex 'ash (FreeBSD 11.0 ff)' ;; esac e=0; case `(PATH=;exp 0)2>&1` in 0) e=1;;esac # Later dash removed the "exp" built-in. n=0; case y in [^x]) n=1;;esac # Some dash and busybox use fnmatch() instead of pmatch(). Here, [^..] is equivalent to [!..]. r=1; case `(PATH=;noexist 2>/dev/null) 2>&1` in *not*) r=0 ;; *file*) r=2 ;;esac # If a command is not found, the error message usually (except in some dash) # cannot be redirected in the above way. The redirection is applied to the command # and not to the shell trying to call it. f=0; case `eval 'for i in x;{ echo $i;}' 2>/dev/null` in x) f=1;;esac # Usually {...} is accepted as for loop body , except in some dash. test -z "$debug" || echo debug '$e$n$r$a$f: ' $e$n$r$a$f case $e$n$r$f in 1100) myex 'ash (dash 0.3.8-30 - 0.4.6)' ;; 1110) myex 'ash (dash 0.4.7 - 0.4.25)' ;; 1010) myex 'ash (dash 0.4.26 - 0.5.2)' ;; 0120|1120|0100) myex 'ash (Busybox 0.x)' ;; 0110) myex 'ash (Busybox 1.x)' ;;esac a=0; case `eval 'x=1;(echo $((x)) )2>/dev/null'` in 1) a=1;;esac # Arithmetic expansion has not been checked earlier because ash which have not # implemented it, stumble really hard over it. x=0; case `f(){ echo $?;};false;f` in 1) x=1;;esac # One dash fix: is the previous exit status preserved upon entering a function? # Another dash fix: are unknown escape sequences printed literally? # The window between these two dash fixes suggests that it is the Slackware variant. c=0; case `echo -e '\x'` in *\\x) c=1;;esac test -z "$debug" || echo debug '$e$n$r$f$a$x$c: ' $e$n$r$f$a$x$c case $e$n$r$f$a$x$c in 1001010) myex 'ash (Slackware 8.1 ff, dash 0.3.7-11 - 0.3.7-14)' ;; 10010??) myex 'ash (dash 0.3-1 - 0.3.7-10, NetBSD 1.2 - 3.1/4.0)' ;; 10011*) myex 'ash (NetBSD 3.1/4.0 ff)' ;; 00101*) myex 'ash (dash 0.5.5.1 ff)' ;; 00100*) myex 'ash (dash 0.5.3-0.5.5)' ;; *) myex 'unknown ash' ;;esac } savedbg=$! # save unused $! for a later check # Korn shell ksh93, $KSH_VERSION not implemented before 93t' # protected: fatal substitution error in non-ksh ( eval 'test "x${.sh.version}" != x' ) 2>/dev/null & wait $! && { eval 'PATH=;case $(XtInitialize 2>&1) in Usage*) DTKSH=" (dtksh/CDE variant)";;esac myex "ksh93 ${.sh.version}${DTKSH}"'; } # Korn shells use a special version variable syntax which is otherwise invalid, # to avoid that it is set in other shells. Avoid another shell stumbling (hard) over # this by protecting it with eval, and (not enough) putting it into the background. # This is an evil hack to keep any other shell running which is unknown and hits this. # # There's a dtksh variant (probably only 93d) which implements a bunch of built-ins # to interact with X and Motif. XtInitialize is one of these built-ins. # Korn shell ksh86/88 _XPG=1;test "`typeset -Z2 x=0; echo $x`" = '00' && { # IRIX ksh does not implement $( ) if called as "sh", except _XPG is set to 1. # The typeset format is ksh specific. case `print -- 2>&1` in *"bad option"*) myex 'ksh86 Version 06/03/86(/a)';; esac # ksh86 stumbles here. test "$savedbg" = '0'&& myex 'ksh88 Version (..-)11/16/88 (1st release)' # ksh88a wrongly sets $! to 0 instead of "nothing" if no bg job has been executed yet. test ${x-"{a}"b} = '{ab}' && myex 'ksh88 Version (..-)11/16/88a' # ...instead of expanding to {a}b since ksh88b. case "`for i in . .; do echo ${i[@]} ;done 2>&1`" in "subscript out of range"*) myex 'ksh88 Version (..-)11/16/88b or c' ;; esac # This was fixed with ksh88d. # No check implemented yet to distinguish between b and c. test "`whence -v true`" = 'true is an exported alias for :' && myex 'ksh88 Version (..-)11/16/88d' test "`(cd /dev/null 2>/dev/null; echo $?)`" != '1' && myex 'ksh88 Version (..-)11/16/88e' # pre-ksh88f abort execution if cd cannot change the directory. test "`(: $(</file/notexistent); echo x) 2>/dev/null`" = '' && myex 'ksh88 Version (..-)11/16/88f' # pre-ksh88g abort execution if this redirection fails. case `([[ "-b" > "-a" ]]) 2>&1` in *"bad number"*) \ myex 'ksh88 Version (..-)11/16/88g';;esac # fixed in OSR5euc # A special bug in ksh88g. test "`cd /dev;cd -P ..;pwd 2>&1`" != '/' && myex 'ksh88 Version (..-)11/16/88g' # fixed in OSR5euc # pre-ksh88h wrongly do not change directory with cd -P .. if you are one below /. test "`f(){ typeset REPLY;echo|read;}; echo dummy|read; f; echo $REPLY`" = "" && myex 'ksh88 Version (..-)11/16/88h' # In pre-ksh88i read wrongly uses the global REPLY variable if a local has been declared with typeset. test $(( 010 )) = 8 && myex 'ksh88 Version (..-)11/16/88i (posix octal base)' # The posix variant on SunOS ksh88i recognizes octal base notation, in accordance with POSIX. myex 'ksh88 Version (..-)11/16/88i' } echo 'oh dear, unknown shell. mascheck@in-ulm.de would like to know this'
Comments to Sven Mascheck <mascheck@in-ulm.de>
<http://www.in-ulm.de/~mascheck/various/whatshell/whatshell.sh.comments.html>