============
Bugs in TCSH
============
-IAN! idallen@ncf.ca
April 2002
--------------------------------------------------------------------------------
| *FIXED*
| From: idallen
| Subject: Can't redirect output of "source"
| % echo "date" >file
| % source file >output
| Thu Sep 3 17:47:19 EDT 1987
--------------------------------------------------------------------------------
From: idallen
Subject: nice is not cumulative
% nice date
% nice nice date
Both have a nice of 4; nice does not accumulate.
From: idallen
Subject: no warning on integer overflow
% @ x=99999999999999999999999
% echo $x
-159383553
From: idallen
Subject: goto seeks backwards in terminal input
% goto x
goto? ignored
goto? ignored
goto? ignored
goto? x:
% goto x
The terminal is now hung - you have to break out.
From: idallen
Subject: nice applied to too many commands
% nice +20 simple `long`
The CSH shell applies the nice to both commands "simple" and "long".
From: idallen
Subject: redirection always happens in single-line "if"
if ( 0 ) echo hi > date
The file date is created empty.
From: idallen
Subject: Expanding variable with newline generates syntax error
% set x="abc\
def"
% echo "$x"
Unmatched ".
From: idallen
Subject: Expanding variable with newline generates extra word
% set x="abc\
def"
% echo $x
abc def
% set y=( $x ) ; echo $#y
3
From: idallen
Subject: Modifier ":e" doesn't work on history
CSH is missing an entry in a case statement for it.
From: idallen
Subject: Shell messages appear on stdout; get redirected
If a program in a shell script exits with a signal that the shell
reports (e.g. Terminated), the report appears on standard output
and if the output of the shell script is redirected the report
gets sent there and you never find out.
From: Steve Hayman <sahayman>
Subject: No error message given for failure to NICE
% nice -10 date
Fri May 30 12:11:12 EDT 1986
CSH never checks the error returns from nice().
From: Ray Butterworth <rbutterworth>
Subject: CSH history reading takes '#' as a comment
% echo a b # c d
a b # c d
% exit
% login
% history
...
99 echo a b
'#' indicates a comment when reading from a shell script file,
and of course CSH thinks it is reading from a file when it reads
the history back in.
From: idallen
Subject: csh: No current job, even if only one job
% somecommand ^Z
Suspended
% bg
[1] somecommand &
% fg
fg: No current job.
The C shell always turns off the current job indicator for a job
that is put in the background with "bg" -- even if it is the only job.
From: idallen (Ian! D. Allen)
Subject: Redirection ignored inside if ( { cmd >xxx } ) ....
% if ( { date >out } ) echo hi
Sun Apr 14 13:24:31 EDT 2002
hi
The shell does not set up its file descriptors for the forked
command. The redirection is completely ignored.
>From idallen
Subject: Error in CSH script causes script exit
If a script has an error in a built-in command (e.g. redirection file not
found), the script exits instead of continuing.
From: idallen (Ian! D. Allen)
Subject: Variables $$, $# don't accept :-modifiers
echo $$:q $#:q
12345:q 0:q
From: idallen (Ian! D. Allen)
Subject: Variable $* (a synonym for argv) doesn't accept subscripts.
% set argv=( a b c d )
% echo $argv[2]
b
% echo $*[2]
echo: No match.
>From idallen
Subject: Using WHICH from CSH
The WHICH command tells the wrong thing if you've created
a new file and haven't done a REHASH. WHICH thinks you
get the new file, but the CSH will give you the old one.
From: idallen (Ian! D. Allen)
Subject: Redirected input to built-in functions misbehaves badly
% date | echo hi
hi
% % jobs
[1] + Running date |
Note the duplicate prompt and spurious job entry.
% % date | echo hi
hi
% % date | echo hi
hi
% % jobs
[1] + Running date |
[2] - Running date |
[3] Running date |
% fg
date |
% fg
date |
fg: No such job (badjob).
% fg
[tcsh shell hangs here in an infinite loop]
Just a general mess of mishandled processes.
From: idallen (Ian! D. Allen)
Subject: stopped pipes generate spurious job ID
% date | sleep 99
^Z
Suspended
[1] 123 456
>From idallen(idallen )
Subject: NICE and NOHUP have no effect as last component of sub-shells.
% nice +10 ps -laxtd0
UID PID PPID CP PRI NI RSS WCHAN STAT TT TIME COMMAND
47 3559 1 0 15 0 33 ff000 S d0 0:16 -csh (csh)
47 7606 3559125 76 10 23 R N d0 0:01 ps -laxtd0
% (nice +10 ps -laxtd0)
UID PID PPID CP PRI NI RSS WCHAN STAT TT TIME COMMAND
47 3559 1 3 15 0 33 ff000 S d0 0:16 -csh (csh)
47 7605 3559 92 48 0 23 R d0 0:01 ps -laxtd0
% (nice ps lx)
... Shows no nice.
% (nice ps lx;date)
... Works.
% (nohup sleep 999)&
... Doesn't ignore SIGHUP.
% (nohup sleep 999;date)&
... Works.
% echo `nice ps lx >/dev/tty`
... Shows no nice.
% echo `nice ps lx >/dev/tty;date`
... Works.
% echo `nohup sleep 999`
... Doesn't ignore SIGHUP.
% echo `nohup sleep 999;date`
... Works.
>From idallen
Subject: you can't nest back-quotes
% echo ` echo \`pwd\` `
Unmatched `.
From: idallen (Ian! D. Allen)
Subject: GLOB not applied to names in setenv or unsetenv
% setenv `echo abc` def
It doesn't set abc, it sets the nasty variable: `echo abc`
% unsetenv `echo abc def ghi`
Doesn't unset abc or def or ghi
>From idallen Thu Mar 15 09:48:35 1984
Subject: Stopping jobs in list of command names throws away the rest.
% a ; b ; c
CSH documents that if you stop B, C will immediately start.
It doesn't. The rest of the list gets thrown away.
From: idallen (Ian! D. Allen)
Subject: Stopping jobs in source'd file aborts the rest of the file.
With the file TEST containing:
mail
echo Hi There you never see this
and typing
% source TEST
and then using ^Z to stop MAIL, the rest of the TEST file is abandoned.
This is especially annoying in one's .login or .cshrc.
>From idallen
Subject: CSH doesn't handle EXIT when it sees it.
% date; exit 99 ; date ; date
Wed Mar 14 19:21:51 EST 1984
Wed Mar 14 19:21:52 EST 1984
Wed Mar 14 19:21:53 EST 1984
The shell doesn't flush pending input when the EXIT is seen.
The shell then exits with status 0 instead of status 99.
>From idallen
Subject: CSH mishandles suspend in subshells.
% ( date; suspend; date )
Sun Mar 4 01:28:28 EST 1984
Suspended
% fg
( date; suspend; date )
Suspended (tty input)
...and you can never get it started again.
>From idallenSun Mar 18 01:28:16
Subject: ECHO mis-handles interrupts and errors in back-quotes
% echo `sleep 999`
<hit break>
[1] 24244
% jobs
[1] Interrupt ` ... `
Note the inability of CSH to tell you the command name used inside
the back-quotes.
>From idallen
Subject: CSH botches $#X where X is environment var
% echo $#path
4
% echo $#PATH
/usr/ucb:/bin:/usr/bin:/usr/public
>From idallen Wed Apr 18, 1984
Subject: Inconsistent handling of variables
The manual says that "set x=word" assigns a single word to x.
To assign multiple words, one is supposed to use "set x=(words)".
But, CSH allows "set x=`date`", which sets x to the many words
resulting from `date`, and $x[1] prints "Mon".
One observes that if x and y are single-word variables, the statements:
% set x=word2
% set y[1]=word2
are identical; both replace the contents of the variable with word2.
But, you can't assign a word to y[1] if y doesn't exist, even though
you can (of course) assign a word to plain "y" if y doesn't exist.
>From idallen(Ian! D. Allen)
Subject: extra next level when nested single-line IF line ends in THEN
Any IF line that ends in THEN is taken as another nesting level, and
requires a corresponding ENDIF:
if ( 0 ) then
if ( 0 ) echo This line ends with then
endif
echo You do not see this.
endif # This shouldn't be needed; but it is.
echo Now you do.
>From idallen
Subject: EXEC doesn't close the file descriptors
/* This program will demonstrate that CSH leaves internal
* file descriptors open across an EXEC built-in command.
*
* % exec ./a.out
*/
main()
{
int i;
for( i=0; i < 20; i++ ){
printf("%d = %d\n", i, isatty(i) );
}
}
The output shows:
> exec ./a.out
0 = 1
1 = 1
2 = 1
3 = 1
4 = 1
5 = 1
6 = 0
7 = 0
8 = 0
9 = 0
...
From: idallen
Subject: can't test success of CD, CHDIR, etc.
cd nosuchdir || echo CD failed
cd nosuchdir && echo CD failed
cd nosuchdir ; echo CD failed
None of the above work in CSH.
>From idallen Mon Dec 16 21:40:32 1985
Subject: GLOB loses memory on directories
echo /*/*/*
If you interrupt the above GLOB, CSH loses memory.
From: idallen
Subject: C Shells don't parse when looking for labels.
The shells just look at the first word on each line. You can
cause the shell to branch in to the middle of a HERE document:
#!/bin/csh -f
onintr quit
sleep 999
cat << EOF
quit:
echo Amazing how this prints.
exit 88 # this exit is taken when break is hit
EOF
quit:
echo You never get here.
>From arwhite Thu Aug 26 13:53:58 1982
Subject: CSH/Bourne shell inconsistent newlines
"`command`" deletes newlines from the command in the cshell, not in the
Bourne shell.
>From idallen (Ian! D. Allen)
Subject: aliases aren't seen after redirection
% date >x
% >x date
% alias foo date
% foo >x
% >x foo
foo: Command not found.
>From idallen (Ian! D. Allen)
Subject: $< misbehaves in pipes
% date | /bin/echo aaa $< bbb
abcdef
aaa a bbb
% bcdef
bcdef: Command not found.
>From chris@pixutl.UUCP (chris) Fri Oct 5 14:01:13 1984
Subject: bug in CSH (history)
There are a couple of bugs in the 'history' command of /bin/csh (and
offspring, such as newcsh):
1) The maximum number of arguments to the history command is set to 2.
% history -h -r 2 # fails
>From idallen
Subject: C Shell expression operators explained
Some odd CSH context-sensitive features. There is ambiguity on how
!~ != and !( should be interpreted:
1 - % ~idallen/study # a valid command line
2 - % !~ # doesn't work
3 - % echo " !~ " # no history
4 - % if ( abc !~ def ) echo hi
1 - % =xxx # a valid command line
2 - % != # doesn't work
3 - % echo " != " # no history
4 - % if ( 1 != 2 ) echo hi
1 - % ( date ) # a valid command line
2 - % !( # doesn't work
3 - % echo " !( " # no history
4 - % if ( !( 1 + 1 ) ) echo hi
The C Shell parser isn't clever enough to distinguish any of cases 2,
3, or 4, so it always behaves as if the character pair was part of an
expression, not a history substitution.
--------------------------------------------------------------------------------
| *NOT A BUG*
| >From idallenThu Jun 27 08:20:08 1985
| Subject: Re: Using > vs. | on shell built-in commands.
|
| CSH cannot put the output of the JOBS command into a pipe. In fact,
| the output is going into the pipe, but the output is empty. You
| couldn't know this, but these shells implement piped built-in commands
| by forking the shell to create an independent process for which the
| main shell can wait. But the internal process table is cleaned
| out after a fork(), since a forked shell is just like a subshell
| and must have its own clean process table in which to enter its own
| running jobs. So by the time the JOBS command executes, it's in a
| child shell that has no jobs running. Hence, the output is empty.
| "echo `jobs`" and "( jobs )" are both empty, for the same reason.
--------------------------------------------------------------------------------
From: jjg@security.UUCP (Jeff Glass)
Subject: csh and I/O redirection
put these four lines in a file, say cshtest :
#! /bin/csh -f
cat << END | ( sh & )
echo hi there
END
( the intent is to send some commands to sh to be executed in the
background, without csh printing the job number of the sh. )
now, from csh, enter the command
source cshtest
and note that you see the message "hi there".
now enter the commands
chmod +x cshtest
./cshtest
and you get no output.
removing either the parentheses or the ampersand causes the message
to appear, but not quietly in the background. I don't understand why
it works when source'd but not when exec'd, either.
--------------------------------------------------------------------------------
| *FIXED*
| From: matt@prism.UUCP
| Subject: Pointless csh puzzle
|
| Here's a pointless little csh puzzle: In the c-shell, it is
| possible to set and environment variable whose name consist of
| more than one word, in the obvious way:
|
| % setenv "FOO BAR" quux
|
| The printenv builtin will show it residing happily in the
| environment. Now for the puzzle: can anyone find a way to GET
| TO the value of this variable, using only csh builtins? In
| other words, is there an <expression> such that
|
| % echo <expression>
|
| will print "quux" on the screen, where <expression> is formed
| only from csh commands?
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
| *FIXED*
| >From tim@ISM780B.UUCP Wed Nov 20 18:00:00 1985
| Subject: Re: C-shell puzzles
|
| Here's another good C shell quirk:
|
| $ echo foo
| foo
| $ repeat 3 echo foo
| foo
| foo
| foo
| $ repeat 3 repeat 3 echo foo
| foo
| foo
| foo
| foo
| foo
| $ repeat $N repeat $M echo foo # $N and $M are integers
| [ $N + $M - 1 foo's ]
| $ repeat $N1 repeat $N2 ... repeat $Nk echo foo
| [ $N1 + $N2 + ... + $Nk - k + 1 foo's ]
| $
--------------------------------------------------------------------------------
>From pur-ee!uiucdcsb!liberte Mon Dec 30 23:20:31 EST 1985
Subject: Csh null strings
There are at least two different-sized null strings in csh.
But sometimes they are equal anyway.
% set x = ""
% set y = "`echo`"
% echo $#x $#y
1 0
% set x =
% set y = `echo`
% echo $#x $#y
1 0
% set x = ("")
% set y = ("`echo`")
% echo $#x $#y
1 0
% set x = ()
% set y = (`echo`)
% echo $#x $#y
0 0
% if (() == "`echo`") echo huh
% if (() == ("`echo`")) echo huh
huh
% if ("" == ("`echo`")) echo huh
% if ("" == "`echo`") echo "huh?"
huh?
>On Jul 18, 8:15am, mark@peek.org (Mark Peek) wrote:
>-- Subject: Updated tcsh-6.12.0 release date?
>
>| Hi Christos,
>| I know I've been (part of) the cause of slipping the release date out
>| for tcsh-6.12.0. :-) Do you have an updated date for releasing it?
>| I'm trying to determine whether it will fit in the time frame for
>| shipment with the next FreeBSD 5.0-DP release.
>
>I hope to release it sometime next week. There are only minor changes in it.
>Is that convenient, or would you like me to push it more?
I sent a note to the FreeBSD release engineers and they're inclined
to hold off on including the new version in the release which they're
branching later today. If DP2 slips out a bit they might consider
including it. I'd say go ahead with your current schedule and I'll
import it whenever it is available. I definitely will be including it
into the next -stable FreeBSD 4.7 release.
BTW, one of the release engineers pointed out a bug with using
jobcmd. If you use the example in the book to update an xterm and
then run something like
grep bar `cat file.list`
It screws up the xterm title bar containing "Faulty alias 'jobcmd'
removed" plus the list of files from the cat command.
The good news is that I was able to reproduce this at home last
night. The bad news is that it is working fine right now here at
work. Oh wait, let me log in remotely and look at the alias I was
using...got it! The command fails if you use:
alias jobcmd 'echo -n "^[]2;\!#^G"'
but works fine if you use: (note the switch of ' and " quotes)
alias jobcmd "echo -n '^[]2;\!#^G'"
Note: I used the above by vi'ing a file and sourcing it from the shell.
If you can confirm, I think this just needs to be updated in the man page.
>Thanks for all the help BTW...
No problem. I like fixing bugs and contributing code...especially for
a great piece of software like tcsh that I use *all* the time. Thank
you for keeping it going!
Mark
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