I need to automate a huge interactive Tcl program using Tcl expect.
As I realized, this territory is really dangerous, as I need to extend the already existing mass of code, but I can't rely on errors actually causing the program to fail with a positive exit code as I could in a regular script.
This means I have to think about every possible thing that could go wrong and "expect" it.
What I currently do is use a "die" procedure instead of raising an error in my own code, that automatically exits. But this kind of error condition can not be catched, and makes it hard to detect errors especially in code not written by me, since ultimately, most library routines will be error-based.
Since I have access to the program's Tcl shell, is it possible to enable fail-on-error?
EDIT:
I am using Tcl 8.3, which is a severe limitation in terms of available tools.
Examples of errors I'd like to automatically exit on:
% puts $a(2)
can't read "a(2)": no such element in array
while evaluating {puts $a(2)}
%
% blublabla
invalid command name "blublabla"
while evaluating blublabla
%
As well as any other error that makes a normal script terminate.
These can bubble up from 10 levels deep within procedure calls.
I also tried redefining the global error command, but not all errors that can occur in Tcl use it. For instance, the above "command not found" error did not go through my custom error procedure.
Since I have access to the program's Tcl shell, is it possible to
enable fail-on-error?
Let me try to summarize in my words: You want to exit from an interactive Tcl shell upon error, rather than having the prompt offered again?
Update
I am using Tcl 8.3, which is a severe limitation in terms of available
tools [...] only source patches to the C code.
As you seem to be deep down in that rabbit hole, why not add another source patch?
--- tclMain.c 2002-03-26 03:26:58.000000000 +0100
+++ tclMain.c.mrcalvin 2019-10-23 22:49:14.000000000 +0200
## -328,6 +328,7 ##
Tcl_WriteObj(errChannel, Tcl_GetObjResult(interp));
Tcl_WriteChars(errChannel, "\n", 1);
}
+ Tcl_Exit(1);
} else if (tsdPtr->tty) {
resultPtr = Tcl_GetObjResult(interp);
Tcl_GetStringFromObj(resultPtr, &length);
This is untested, the Tcl 8.3.5 sources don't compile for me. But this section of Tcl's internal are comparable to current sources, tested using my Tcl 8.6 source installation.
For the records
With a stock shell (tclsh), this is a little fiddly, I am afraid. The following might work for you (though, I can imagine cases where this might fail you). The idea is
to intercept writes to stderr (this is to where an interactive shell redirects error messages, before returning to the prompt).
to discriminate between arbitrary writes to stderr and error cases, one can use the global variable ::errorInfo as a sentinel.
Step 1: Define a channel interceptor
oo::class create Bouncer {
method initialize {handle mode} {
if {$mode ne "write"} {error "can't handle reading"}
return {finalize initialize write}
}
method finalize {handle} {
# NOOP
}
method write {handle bytes} {
if {[info exists ::errorInfo]} {
# This is an actual error;
# 1) Print the message (as usual), but to stdout
fconfigure stdout -translation binary
puts stdout $bytes
# 2) Call on [exit] to quit the Tcl process
exit 1
} else {
# Non-error write to stderr, proceed as usual
return $bytes
}
}
}
Step 2: Register the interceptor for stderr in interactive shells
if {[info exists ::tcl_interactive]} {
chan push stderr [Bouncer new]
}
Once registered, this will make your interactive shell behave like so:
% puts stderr "Goes, as usual!"
Goes, as usual!
% error "Bye, bye"
Bye, bye
Some remarks
You need to be careful about the Bouncer's write method, the error message has already been massaged for the character encoding (therefore, the fconfigure call).
You might want to put this into a Tcl package or Tcl module, to load the bouncer using package req.
I could imagine that your program writes to stderr and the errorInfo variable happens to be set (as a left-over), this will trigger an unintended exit.
I go
export PERL6LIB="/GitHub/perl6-Units/lib"
and then
echo $PERL6LIB
/GitHub/perl6-Units/lib
But when I run perl6 t/01-basic.t
use v6;
use Test;
plan 3;
lives-ok {
use Units <m>;
ok #Units::UNITS.elems > 0;
ok (0m).defined;
}
done-testing;
I still get an error
===SORRY!===
Could not find Units at line 8 in:
/Users/--me--/.perl6
/usr/local/Cellar/rakudo-star/2018.01/share/perl6/site
/usr/local/Cellar/rakudo-star/2018.01/share/perl6/vendor
/usr/local/Cellar/rakudo-star/2018.01/share/perl6
CompUnit::Repository::AbsolutePath<140707489084448>
CompUnit::Repository::NQP<140707463117264>
CompUnit::Repository::Perl5<140707463117304>
In Perl 5 I would have used print "#INC"; to see what paths are searched for the lib before the error is thrown. Using say flat $*REPO.repo-chain.map(*.loaded); either is before it loads or after it throws the exception.
Any help would be much appreciated - or maybe a hint on what to put in ~/.perl6 as I can't get a symlink to work either.
The error message itself is telling you what the library paths available are. You are failing to print them because you are expecting a run time action ( say ) to take place before a compile time error -- you could print out $*REPO at compile time, but again the exception is already showing you what you wanted.
$ PERL6LIB="/GitHub/perl6-Units/lib" perl6 -e 'BEGIN say $*REPO.repo-chain; use Foo;'
(file#/GitHub/perl6-Units/lib inst#/Users/ugexe/.perl6 inst#/Users/ugexe/.rakudobrew/moar-2018.08/install/share/perl6/site inst#/Users/ugexe/.rakudobrew/moar-2018.08/install/share/perl6/vendor inst#/Users/ugexe/.rakudobrew/moar-2018.08/install/share/perl6 ap# nqp# perl5#)
===SORRY!===
Could not find Foo at line 1 in:
/GitHub/perl6-Units/lib
/Users/ugexe/.perl6
/Users/ugexe/.rakudobrew/moar-2018.08/install/share/perl6/site
/Users/ugexe/.rakudobrew/moar-2018.08/install/share/perl6/vendor
/Users/ugexe/.rakudobrew/moar-2018.08/install/share/perl6
CompUnit::Repository::AbsolutePath<140337382425072>
CompUnit::Repository::NQP<140337350057496>
CompUnit::Repository::Perl5<140337350057536>
You can see /GitHub/perl6-Units/lib is showing up in the available paths, which is unlike your example. I'd question if your shell/env is actually setup correctly.
I have a problem with ksh in that a while loop is failing to obey the "while" condition. I should add now that this is ksh88 on my client's Solaris box. (That's a separate problem that can't be addressed in this forum. ;) I have seen Lance's question and some similar but none that I have found seem to address this. (Disclaimer: NO I haven't looked at every ksh question in this forum)
Here's a very cut down piece of code that replicates the problem:
1 #!/usr/bin/ksh
2 #
3 go=1
4 set -x
5 tail -0f loop-test.txt | while [[ $go -eq 1 ]]
6 do
7 read lbuff
8 set $lbuff
9 nwords=$#
10 printf "Line has %d words <%s>\n" $nwords "${lbuff}"
11 if [[ "${lbuff}" = "0" ]]
12 then
13 printf "Line consists of %s; time to absquatulate\n" $lbuff
14 go=0 # Violate the WHILE condition to get out of loop
15 fi
16 done
17 printf "\nLooks like I've fallen out of the loop\n"
18 exit 0
The way I test this is:
Run loop-test.sh in background mode
In a different window I run commands like "echo some nonsense >>loop_test.txt" (w/o the quotes, of course)
When I wish to exit, I type "echo 0 >>loop-test.txt"
What happens? It indeed sets go=0 and displays the line:
Line consists of 0; time to absquatulate
but does not exit the loop. To break out I append one more line to the txt file. The loop does NOT process that line and just falls out of the loop, issuing that "fallen out" message before exiting.
What's going on with this? I don't want to use "break" because in the actual script, the loop is monitoring the log of a database engine and the flag is set when it sees messages that the engine is shutting down. The actual script must still process those final lines before exiting.
Open to ideas, anyone?
Thanks much!
-- J.
OK, that flopped pretty quick. After reading a few other posts, I found an answer given by dogbane that sidesteps my entire pipe-to-while scheme. His is the second answer to a question (from 2013) where I see neeraj is using the same scheme I'm using.
What was wrong? The pipe-to-while has always worked for input that will end, like a file or a command with a distinct end to its output. However, from a tail command, there is no distinct EOF. Hence, the while-in-a-subshell doesn't know when to terminate.
Dogbane's solution: Don't use a pipe. Applying his logic to my situation, the basic loop is:
while read line
do
# put loop body here
done < <(tail -0f ${logfile})
No subshell, no problem.
Caveat about that syntax: There must be a space between the two < operators; otherwise it looks like a HEREIS document with bad syntax.
Er, one more catch: The syntax did not work in ksh, not even in the mksh (under cygwin) which emulates ksh93. But it did work in bash. So my boss is gonna have a good laugh at me, 'cause he knows I dislike bash.
So thanks MUCH, dogbane.
-- J
After articulating the problem and sleeping on it, the reason for the described behavior came to me: After setting go=0, the control flow of the loop still depends on another line of data coming in from STDIN via that pipe.
And now that I have realized the cause of the weirdness, I can speculate on an alternative way of reading from the stream. For the moment I am thinking of the following solution:
Open the input file as STDIN (Need to research the exec syntax for that)
When the condition occurs, close STDIN (Again, need to research the syntax for that)
It should then be safe to use the more intuitive:while read lbuffat the top of the loop.
I'll test this out today and post the result. I'd hope someone else benefit from the method (if it works).
When I run ANY test I get the same message. Here is an example test:
package require tcltest
namespace import -force ::tcltest::*
test foo-1.1 {save 1 in variable name foo} {} {
set foo 1
} {1}
I get the following output:
WARNING: unknown option -run: should be one of -asidefromdir, -constraints, -debug, -errfile, -file, -limitconstraints, -load, -loadfile, -match, -notfile, -outfile, -preservecore, -relateddir, -singleproc, -skip, -testdir, -tmpdir, or -verbose
I've tried multiple tests and nothing seems to work. Does anyone know how to get this working?
Update #1:
The above error was my fault, it was due to it being run in my script. However if I run the following at a command line I got no output:
[root#server1 ~]$ tcl
tcl>package require tcltest
2.3.3
tcl>namespace import -force ::tcltest::*
tcl>test foo-1.1 {save 1 in variable name foo} {expr 1+1} {2}
tcl>echo [test foo-1.1 {save 1 in variable name foo} {expr 1+1} {2}]
tcl>
How do I get it to output pass or fail?
You don't get any output from the test command itself (as long as the test passes, as in the example: if it fails, the command prints a "contents of test case" / "actual result" / "expected result" summary; see also the remark on configuration below). The test statistics are saved internally: you can use the cleanupTests command to print the Total/Passed/Skipped/Failed numbers (that command also resets the counters and does some cleanup).
(When you run runAllTests, it runs test files in child processes, intercepting the output from each file's cleanupTests and adding them up to a grand total.)
The internal statistics collected during testing is available in AFACT undocumented namespace variables like ::tcltest::numTests. If you want to work with the statistics yourself, you can access them before calling cleanupTests, e.g.
parray ::tcltest::numTests
array set myTestData [array get ::tcltest::numTests]
set passed $::tcltest::numTests(Passed)
Look at the source for tcltest in your library to see what variables are available.
The amount of output from the test command is configurable, and you can get output even when the test passes if you add p / pass to the -verbose option. This option can also let you have less output on failure, etc.
You can also create a command called ::tcltest::ReportToMaster which, if it exists, will be called by cleanupTests with the pertinent data as arguments. Doing so seems to suppress both output of statistics and at least most resetting and cleanup. (I didn't go very far in investigating that method.) Be aware that messing about with this is more likely to create trouble than solve problems, but if you are writing your own testing software based on tcltest you might still want to look at it.
Oh, and please use the newer syntax for the test command. It's more verbose, but you'll thank yourself later on if you get started with it.
Obligatory-but-fairly-useless (in this case) documentation link: tcltest
It's the first great virtue of programmers. All of us have, at one time or another automated a task with a bit of throw-away code. Sometimes it takes a couple seconds tapping out a one-liner, sometimes we spend an exorbitant amount of time automating away a two-second task and then never use it again.
What tiny hack have you found useful enough to reuse? To make go so far as to make an alias for?
Note: before answering, please check to make sure it's not already on favourite command-line tricks using BASH or perl/ruby one-liner questions.
i found this on dotfiles.org just today. it's very simple, but clever. i felt stupid for not having thought of it myself.
###
### Handy Extract Program
###
extract () {
if [ -f $1 ] ; then
case $1 in
*.tar.bz2) tar xvjf $1 ;;
*.tar.gz) tar xvzf $1 ;;
*.bz2) bunzip2 $1 ;;
*.rar) unrar x $1 ;;
*.gz) gunzip $1 ;;
*.tar) tar xvf $1 ;;
*.tbz2) tar xvjf $1 ;;
*.tgz) tar xvzf $1 ;;
*.zip) unzip $1 ;;
*.Z) uncompress $1 ;;
*.7z) 7z x $1 ;;
*) echo "'$1' cannot be extracted via >extract<" ;;
esac
else
echo "'$1' is not a valid file"
fi
}
Here's a filter that puts commas in the middle of any large numbers in standard input.
$ cat ~/bin/comma
#!/usr/bin/perl -p
s/(\d{4,})/commify($1)/ge;
sub commify {
local $_ = shift;
1 while s/^([ -+]?\d+)(\d{3})/$1,$2/;
return $_;
}
I usually wind up using it for long output lists of big numbers, and I tire of counting decimal places. Now instead of seeing
-rw-r--r-- 1 alester alester 2244487404 Oct 6 15:38 listdetail.sql
I can run that as ls -l | comma and see
-rw-r--r-- 1 alester alester 2,244,487,404 Oct 6 15:38 listdetail.sql
This script saved my career!
Quite a few years ago, i was working remotely on a client database. I updated a shipment to change its status. But I forgot the where clause.
I'll never forget the feeling in the pit of my stomach when I saw (6834 rows affected). I basically spent the entire night going through event logs and figuring out the proper status on all those shipments. Crap!
So I wrote a script (originally in awk) that would start a transaction for any updates, and check the rows affected before committing. This prevented any surprises.
So now I never do updates from command line without going through a script like this. Here it is (now in Python):
import sys
import subprocess as sp
pgm = "isql"
if len(sys.argv) == 1:
print "Usage: \nsql sql-string [rows-affected]"
sys.exit()
sql_str = sys.argv[1].upper()
max_rows_affected = 3
if len(sys.argv) > 2:
max_rows_affected = int(sys.argv[2])
if sql_str.startswith("UPDATE"):
sql_str = "BEGIN TRANSACTION\\n" + sql_str
p1 = sp.Popen([pgm, sql_str],stdout=sp.PIPE,
shell=True)
(stdout, stderr) = p1.communicate()
print stdout
# example -> (33 rows affected)
affected = stdout.splitlines()[-1]
affected = affected.split()[0].lstrip('(')
num_affected = int(affected)
if num_affected > max_rows_affected:
print "WARNING! ", num_affected,"rows were affected, rolling back..."
sql_str = "ROLLBACK TRANSACTION"
ret_code = sp.call([pgm, sql_str], shell=True)
else:
sql_str = "COMMIT TRANSACTION"
ret_code = sp.call([pgm, sql_str], shell=True)
else:
ret_code = sp.call([pgm, sql_str], shell=True)
I use this script under assorted linuxes to check whether a directory copy between machines (or to CD/DVD) worked or whether copying (e.g. ext3 utf8 filenames -> fusebl
k) has mangled special characters in the filenames.
#!/bin/bash
## dsum Do checksums recursively over a directory.
## Typical usage: dsum <directory> > outfile
export LC_ALL=C # Optional - use sort order across different locales
if [ $# != 1 ]; then echo "Usage: ${0/*\//} <directory>" 1>&2; exit; fi
cd $1 1>&2 || exit
#findargs=-follow # Uncomment to follow symbolic links
find . $findargs -type f | sort | xargs -d'\n' cksum
Sorry, don't have the exact code handy, but I coded a regular expression for searching source code in VS.Net that allowed me to search anything not in comments. It came in very useful in a particular project I was working on, where people insisted that commenting out code was good practice, in case you wanted to go back and see what the code used to do.
I have two ruby scripts that I modify regularly to download all of various webcomics. Extremely handy! Note: They require wget, so probably linux. Note2: read these before you try them, they need a little bit of modification for each site.
Date based downloader:
#!/usr/bin/ruby -w
Day = 60 * 60 * 24
Fromat = "hjlsdahjsd/comics/st%Y%m%d.gif"
t = Time.local(2005, 2, 5)
MWF = [1,3,5]
until t == Time.local(2007, 7, 9)
if MWF.include? t.wday
`wget #{t.strftime(Fromat)}`
sleep 3
end
t += Day
end
Or you can use the number based one:
#!/usr/bin/ruby -w
Fromat = "http://fdsafdsa/comics/%08d.gif"
1.upto(986) do |i|
`wget #{sprintf(Fromat, i)}`
sleep 1
end
Instead of having to repeatedly open files in SQL Query Analyser and run them, I found the syntax needed to make a batch file, and could then run 100 at once. Oh the sweet sweet joy! I've used this ever since.
isqlw -S servername -d dbname -E -i F:\blah\whatever.sql -o F:\results.txt
This goes back to my COBOL days but I had two generic COBOL programs, one batch and one online (mainframe folks will know what these are). They were shells of a program that could take any set of parameters and/or files and be run, batch or executed in an IMS test region. I had them set up so that depending on the parameters I could access files, databases(DB2 or IMS DB) and or just manipulate working storage or whatever.
It was great because I could test that date function without guessing or test why there was truncation or why there was a database ABEND. The programs grew in size as time went on to include all sorts of tests and become a staple of the development group. Everyone knew where the code resided and included them in their unit testing as well. Those programs got so large (most of the code were commented out tests) and it was all contributed by people through the years. They saved so much time and settled so many disagreements!
I coded a Perl script to map dependencies, without going into an endless loop, For a legacy C program I inherited .... that also had a diamond dependency problem.
I wrote small program that e-mailed me when I received e-mails from friends, on an rarely used e-mail account.
I wrote another small program that sent me text messages if my home IP changes.
To name a few.
Years ago I built a suite of applications on a custom web application platform in PERL.
One cool feature was to convert SQL query strings into human readable sentences that described what the results were.
The code was relatively short but the end effect was nice.
I've got a little app that you run and it dumps a GUID into the clipboard. You can run it /noui or not. With UI, its a single button that drops a new GUID every time you click it. Without it drops a new one and then exits.
I mostly use it from within VS. I have it as an external app and mapped to a shortcut. I'm writing an app that relies heavily on xaml and guids, so I always find I need to paste a new guid into xaml...
Any time I write a clever list comprehension or use of map/reduce in python. There was one like this:
if reduce(lambda x, c: locks[x] and c, locknames, True):
print "Sub-threads terminated!"
The reason I remember that is that I came up with it myself, then saw the exact same code on somebody else's website. Now-adays it'd probably be done like:
if all(map(lambda z: locks[z], locknames)):
print "ya trik"
I've got 20 or 30 of these things lying around because once I coded up the framework for my standard console app in windows I can pretty much drop in any logic I want, so I got a lot of these little things that solve specific problems.
I guess the ones I'm using a lot right now is a console app that takes stdin and colorizes the output based on xml profiles that match regular expressions to colors. I use it for watching my log files from builds. The other one is a command line launcher so I don't pollute my PATH env var and it would exceed the limit on some systems anyway, namely win2k.
I'm constantly connecting to various linux servers from my own desktop throughout my workday, so I created a few aliases that will launch an xterm on those machines and set the title, background color, and other tweaks:
alias x="xterm" # local
alias xd="ssh -Xf me#development_host xterm -bg aliceblue -ls -sb -bc -geometry 100x30 -title Development"
alias xp="ssh -Xf me#production_host xterm -bg thistle1 ..."
I have a bunch of servers I frequently connect to, as well, but they're all on my local network. This Ruby script prints out the command to create aliases for any machine with ssh open:
#!/usr/bin/env ruby
require 'rubygems'
require 'dnssd'
handle = DNSSD.browse('_ssh._tcp') do |reply|
print "alias #{reply.name}='ssh #{reply.name}.#{reply.domain}';"
end
sleep 1
handle.stop
Use it like this in your .bash_profile:
eval `ruby ~/.alias_shares`