ellis@ultra.dec.com (David Ellis) (07/19/88)
In the csh, the expression $name or ${name} looks up the variable with the
given name and substitutes its value.
Is there any way to get the value of a variable whose name is the value of
another variable?
e.g. if we've done set x=a and set a=3, is there any simple csh expression
in terms of x that yields the value of a (3)?
Csh gives an error message "Variable syntax." if I try something like
echo ${$x}
or even
echo "`echo {\$}$x`"
----
David Ellis
Digital Equipment Corporation -- BXB1-1/D03
85 Swanson Road, Boxboro MA 01719 -- (617) 264-5073
Usenet: {ucbvax,allegra,decvax}!decwrl!ultra.dec.com!ellis
ARPA: ellis%ultra.dec@decwrl.dec.comhd@mh_co2.mh.nl (Theo Hardendood) (07/20/88)
From article <8807191241.AA18881@decwrl.dec.com>, by ellis@ultra.dec.com (David Ellis): > Is there any way to get the value of a variable whose name is the value of > another variable? > e.g. if we've done set x=a and set a=3, is there any simple csh expression > in terms of x that yields the value of a (3)? set a=3 set x=a set test=`eval echo \$$x` Theo Hardendood USENET: hd@mh.nl via European backbone (mcvax). UUCP : ..!mcvax!mhres!mh_co2!hd
mesard@bbn.com (Wayne Mesard) (07/21/88)
From article <8807191241.AA18881@decwrl.dec.com>, by ellis@ultra.dec.com (David Ellis): > Is there any way to get the value of a variable whose name is the value of > another variable? > > e.g. if we've done set x=a and set a=3, is there any simple csh expression > in terms of x that yields the value of a (3)? How 'bout: eval echo \$$x -- unsigned *Wayne_Mesard(); MESARD@BBN.COM BBN, Cambridge, MA When Martin Sheen visited me, he was smoking again after his heart attack, and I asked why. He said, 'It is my friend it is always there and doesn't pass judgment.' I said, 'Your friend is going to kill you.'" - Larry King
ok@quintus.uucp (Richard A. O'Keefe) (07/21/88)
In article <8807191241.AA18881@decwrl.dec.com> ellis@ultra.dec.com (David Ellis) writes: >Is there any way to get the value of a variable whose name is the value of >another variable? >e.g. if we've done set x=a and set a=3, is there any simple csh expression >in terms of x that yields the value of a (3)? One method is to use "eval". E.g. % set x=a a=3 % eval echo '$'$x prints 3 Another method is to exploit the fact that the "set" command with no arguments prints out the shell variables in alphabetic order, one per line, in the form "<name><TAB><value>". So you can do % set | sed -n -e "s/^$x<TAB>//p" where <TAB> is to be replaced by an actual tab character. Rather than using ... `eval echo '$'$x` ... it may be more efficient to use eval set y='$'$x ... $y ... as that doesn't involve forking another shell for the `` form. The Bourne shell also has 'eval' $ x=a a=3 $ eval y='$'$x $ eval echo '$'$x sets y to 3 and prints 3.
greim@sbsvax.UUCP (Michael Greim) (07/25/88)
In article <8807191241.AA18881@decwrl.dec.com>, ellis@ultra.dec.com (David Ellis) writes: < In the csh, the expression $name or ${name} looks up the variable with the < given name and substitutes its value. < < Is there any way to get the value of a variable whose name is the value of < another variable? < < e.g. if we've done set x=a and set a=3, is there any simple csh expression < in terms of x that yields the value of a (3)? < < Csh gives an error message "Variable syntax." if I try something like < echo ${$x} < or even < echo "`echo {\$}$x`" < < ---- < David Ellis Yes. Here it is: eval echo \$$x Works in all csh's I could get my hands on quickly. -mg -- +------------------------------------------------------------------------------+ | UUCP: ...!uunet!unido!sbsvax!greim | Michael T. Greim | | or greim@sbsvax.UUCP | Universitaet des Saarlandes | | CSNET: greim%sbsvax.uucp@Germany.CSnet| FB 10 - Informatik (Dept. of CS) | | ARPA: greim%sbsvax.uucp@uunet.UU.NET | Bau 36, Im Stadtwald 15 | | Phone: +49 681 302 2434 | D-6600 Saarbruecken 11, West Germany | +------------------------------------------------------------------------------+ | # include <disclaimers/std.h> | +------------------------------------------------------------------------------+
mbennett@midas.UUCP (Mike Bennett) (07/26/88)
in article <8807191241.AA18881@decwrl.dec.com>, ellis@ultra.dec.com (David Ellis) says: > > Is there any way to get the value of a variable whose name is the value of > another variable? > > e.g. if we've done set x=a and set a=3, is there any simple csh expression > in terms of x that yields the value of a (3)? > > Csh gives an error message "Variable syntax." if I try something like > echo ${$x} > or even > echo "`echo {\$}$x`" > Try "eval echo \$$x". Eval is a built-in csh (and sh) command which effectively causes the command line to be scanned twice - once by the shell when arguments are passed to eval, and then by the command passed to eval (that's why the first $ is escaped). hope this helps. Mike Bennett Languages Development Gould Computer Systems Division, Ft. Lauderdale, Florida .....!{uunet,sun,pur-ee,brl-smoke}!gould!mbennett I am paid to work and to think for my employer - so I do. I am NOT paid to speak for my employer - so I don't.
mkhaw@teknowledge-vaxc.ARPA (Mike Khaw) (11/25/88)
I use a Bourne shell script that I call "news" to read netnews. I defined
a csh alias
alias news '(checknews -q || \news)'
so that I can run it in either the foreground or the background. It works
fine in both modes, but when it runs in the background and I get notification
it says something like
[1] + Stopped (tty output) ( < ^A > ^A )
Why the "^A"s and the redirection symbols? (This is on ultrix 2.2).
Mike Khaw
--
internet: mkhaw@teknowledge.arpa
uucp: {uunet|sun|ucbvax|decwrl|ames|hplabs}!mkhaw%teknowledge.arpa
hardcopy: Teknowledge Inc, 1850 Embarcadero Rd, POB 10119, Palo Alto, CA 94303chris@mimsy.UUCP (Chris Torek) (11/26/88)
In article <25971@teknowledge-vaxc.ARPA> mkhaw@teknowledge-vaxc.ARPA (Mike Khaw) writes: > [1] + Stopped (tty output) ( < ^A > ^A ) > >Why the "^A"s and the redirection symbols? (This is on ultrix 2.2). Old `csh'es have a bug in the job printing code, such that `||' trees (and, I think, `&&' trees) produce this. -- In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163) Domain: chris@mimsy.umd.edu Path: uunet!mimsy!chris
nodak.edu>@adm.BRL.MIL (05/23/89)
Hello, A friend of mine was playing with our version of the csh on a (mostly) Sys V.2 lookalike system, when the following sequence occured: % set ab = (spi kev ish ere) % echo $ab[1] spi % alias test ' foreach x (1 2 3) \ echo $ab[$x] \ end ' % test ? ? DISCONNECTED from 04/118 Are we doing something incredibly stupid here ? Or do we have a brain damaged version of csh ? We're running sx1100 2R1 on an sperry 1100/91 mainframe with a binary only license. Thanks & please forgive the spelling errors. Patrick Spinler bitnet: pspinler%mkvax1@msus1 115 Parkway Apt 102 Mankato State University Mankato, Minnesota 56001
iwarner@zaphod.axion.bt.co.uk (Ivan Warner,G44 SSTF,6632,) (05/24/89)
From article <19712@adm.BRL.MIL>, by nodak.edu>@adm.BRL.MIL: > > A friend of mine was playing with our version of the csh on a (mostly) > Sys V.2 lookalike system, when the following sequence occured: > > % set ab = (spi kev ish ere) > % echo $ab[1] > spi > % alias test ' foreach x (1 2 3) \ > echo $ab[$x] \ > end ' > % test > ? ? > DISCONNECTED from 04/118 > > Are we doing something incredibly stupid here ? Or do we have a brain damaged > version of csh ? We're running sx1100 2R1 on an sperry 1100/91 mainframe with > a binary only license. > If its any consolation, the Ultrix V3.0 version of csh did the same - it output "? ?", and then logged me out. Run from within a shell script, it does not log me out, but it doesn't do what it should. Running the shell script: set ab = (spi kev ish ere) echo $ab[1] alias test ' foreach x (1 2 3) \ echo $ab[$x] \ end ' alias test echo '--------------------------' sleep 5 test using the command "csh -x cshtest" gives the output: set ab = ( spi kev ish ere ) echo spi spi alias test foreach x (1 2 3) echo $ab[$x] end alias test foreach x (1 2 3) echo $ab[$x] end echo -------------------------- -------------------------- sleep 5 foreach x ( 1 2 3 ) i.e. the script dies at the "foreach" command, but with no error message. Must be a bug in csh.
kamens@Neon.Stanford.EDU (Samuel N Kamens) (11/13/89)
Hi all! I am trying to write a csh shell that looks like this (with names changed to protect the innocent) if ($1 == foo) then /usr/ucb/talk foo@bar else /usr/ucb/talk $1 endif When I run it, I get an error (error: end of file unexpected). It's probably something really silly, but could someone tell me why this is wrong? Thanks, Sam Kamens | "How do you know she is a witch?" kamens@neon.stanford.edu | "She looks like one!!" -- Sam Kamens | "How do you know she is a witch?"
jik@athena.mit.edu (Jonathan I. Kamens) (11/13/89)
In article <1989Nov13.014412.24735@Neon.Stanford.EDU> kamens@Neon.Stanford.EDU (Samuel N Kamens) writes: >I am trying to write a csh shell that looks like this (with names changed to >protect the innocent) > >... > >When I run it, I get an error (error: end of file unexpected). You need "#!/bin/csh -f" at the top. Since you don't have that, it is being interpreted as a bourne shell script, hence the error you received. >Sam Kamens | "How do you know she is a witch?" >kamens@neon.stanford.edu | "She looks like one!!" Jonathan Kamens USnail: MIT Project Athena 11 Ashford Terrace jik@Athena.MIT.EDU Allston, MA 02134 Office: 617-253-8495 Home: 617-782-0710 P.S. For those of you who are wondering, yes.
cpcahil@virtech.uucp (Conor P. Cahill) (11/13/89)
In article <1989Nov13.014412.24735@Neon.Stanford.EDU>, kamens@Neon.Stanford.EDU (Samuel N Kamens) writes: > if ($1 == foo) then > /usr/ucb/talk foo@bar > else > /usr/ucb/talk $1 > endif > > When I run it, I get an error (error: end of file unexpected). This works correctly under the csh, but gives the error you indicate when run under the borne shell, so you are probably not running it under the csh (even though you call it from the csh prompt). To ensure that the csh is used to process it, add the following to the beginning of the file: #!/bin/csh I believe the # must be in column 1. Note that this will not work when the user is using the borne shell as his command interpreter on most non-BSD based systems. -- +-----------------------------------------------------------------------+ | Conor P. Cahill uunet!virtech!cpcahil 703-430-9247 ! | Virtual Technologies Inc., P. O. Box 876, Sterling, VA 22170 | +-----------------------------------------------------------------------+
tbc@large.cray.com (Tom Craig) (06/29/90)
I have a csh question. Is it possible to redirect stdout and stderr to different files in the c shell, (like 1>out 2>err in the bourne shell)? I can't figure out how, and no one has been able to enlighten me. Please email the answer to tbc@crayamid.cray.com. Thanks in advance, -- Tom Craig | The opinions expressed here are not those of CRI, its tbc@crayamid.cray.com | subsidiaries or lackeys. Anyone who says otherwise 612-681-5797 | is itching for a fight. (Thank you, Michael Feldman)
eli@panda.uucp (Eli Taub/100000) (07/02/90)
In article <7267@large.cray.com> tbc@large.cray.com (Tom Craig) writes: >I have a csh question. Is it possible to redirect stdout and stderr to >different files in the c shell, (like 1>out 2>err in the bourne shell)? >I can't figure out how, and no one has been able to enlighten me. Try this: (prog > out) >& err A special case of the above is: (prog > /dev/tty) >& /dev/null that will filter out all stderr. _ |___ Eli Taub | | \ | (512) 838-4810 | /\/ Contractor at (AWD) IBM | I express my apinions not IBM's. / | \
wonus@virtech.uucp (Kevin C. Wonus) (07/09/90)
In article <7267@large.cray.com> tbc@large.cray.com (Tom Craig) writes: >I have a csh question. Is it possible to redirect stdout and stderr to >different files in the c shell, (like 1>out 2>err in the bourne shell)? Yes: (program_name > output) >& error '>&' operator redirects stdout and stderr. Therefore, stdout must be redirected first and is enclosed in () for that reason. After stdout is redirected, the '>&' operator redirects only stderr. Kevin C. Wonus Virtual Technologies Inc. Sterling, Virginia
maart@cs.vu.nl (Maarten Litmaath) (07/10/90)
In article <1990Jul09.150046.4238@virtech.uucp>, wonus@virtech.uucp (Kevin C. Wonus) writes: )In article <7267@large.cray.com> tbc@large.cray.com (Tom Craig) writes: )>I have a csh question. Is it possible to redirect stdout and stderr to )>different files in the c shell, (like 1>out 2>err in the bourne shell)? ) )Yes: ) (program_name > output) >& error ) )'>&' operator redirects stdout and stderr. Therefore, stdout must be )redirected )first and is enclosed in () for that reason. After stdout is redirected, the )'>&' operator redirects only stderr. Right answer, wrong logic. First we create a subshell whose stdout _and_ stderr have been redirected to the file `error'. _In_ the subshell we execute `program_name' with its stdout redirected to the file `output'; we don't mess with its stderr, so that'll still be connected to `error'. The result of it all is stdout going to `output' and _only_ stderr going to `error'. QED -- "and with a sudden plop it lands on usenet. what is it? omigosh, it must[...] be a new user! quick kill it before it multiplies!" (Loren J. Miller)
morgan@chaos.cs.brandeis.edu (Dylan Kaufman) (05/02/91)
Hi, I am trying to write a script which will be run by cron and which will notify me if someone somewhere is logged on. What I mean by that is that the script will check to see whether I am logged on (if not, it doesn't need to bother...) and then (assuming I am) check to see whether there is someone logged onto another account on another computer. If there is, it should then determine what tty I am logged onto and either cat or write to my tty... the problem is that it doesn't work... I get mail from root saying that my cron output is stty: : Not a typewriter. The same thing happens when I try having it send me mail rather than using cat or write. The code I have is as follows: #!/bin/csh set a=`f|fgrep -c morgan` if ($a != 0) then set b=`finger @eris.berkeley.edu|fgrep -c morgan` if ($b != 0) then set c=`w morgan|fgrep morgan|cut -f4 -d' '` cat ~/cronfile > /dev/$c endif endif Any help would be appreciated. Thank you in advance, -- -<>Dylan<>- MA EMT-M, CA EMT-1A, BEMCo 107 Dylan Kaufman Major in Computer Science morgan@chaos.cs.brandeis.edu Brandeis University, Waltham, MA ------<< Support your local Emergency Medical Services >>------- "Don't ask me, I'm just improvising" -RUSH
kre@cs.mu.oz.au (Robert Elz) (05/04/91)
morgan@chaos.cs.brandeis.edu (Dylan Kaufman) writes: >stty: : Not a typewriter. I'd guess that your .cshrc has an "stty" command in it, which will break all kinds of things (it belongs in .login). You could fix that, or try #!/bin/csh -f but you'd be much better off to use #!/bin/sh and rewrite the script in sh. Fix your .cshrc anyway. kre