The expression that is contained within double braces can take many forms, but the general syntax is one of
or
or
Because the strings and filenames do not need to be quoted, there is no way for the interpreter to determine whether xx is a string or a variable name that should be expanded. Thus, you must explicitly dereference the variables you wish to have expanded as you have done in your first working example.
This is different than in arithmetic expressions (( expression )) where the interpreter can assume that any string references are variable names to be evaluated as such.
Hi,
I was trying to use this particular option of grep
grep -r 'Search_pattern' *
This command should ideally search all the occurrences of Search_pattern recursively within a directory & print it on shell prompt. But this command is not doing what is expected. It just displays nothin!
... (8 Replies)
Hi,
I am trying to figure out which version I am running of sendmail, but I am buffed.
This is what I get
sendmail -d0.1 -bt < /dev/null
sendmail: illegal option -- d
Telneting to my host:
~]$ telnet localhost 25
Trying 127.0.0.1...
Connected to localhost.
Escape character is... (1 Reply)
#! /usr/tsch
foreach f (`cat contacts.list`)
awk '{printf ($2 in a) ? ","$5 : (NR>1) ? RS $2 FS $5 : $2 FS $5; a} END{print e}' $f > $f_inter.map
end
My file: cat contacts.list is just a list of files.
I get this error:
doit_contacts2intermap.sh: Command not found.
Thanks! (1 Reply)
Greetings all. :)
I would like to use sed to join all non-blank lines together in a particular file. I was thinking I could do this by simply replacing the terminating, new-line character on every line which is not blank, but I must be missing something in my sed line:
$ sed... (3 Replies)
This is the code:
while test 1 -eq 1
do
read a
$a
if test $a = stop
then
break
fi
done
I read a command on every loop an execute it.
I check if the string equals the word stop to end the loop,but it say that I gave too many arguments to test.
For example echo hello.
Now the... (1 Reply)
awk 'BEGIN{print '1.2449'**0.5}'
awk: line 1: syntax error at or near *
can someone help me troubleshoot the above command?
i'm trying to do the square root of 1.2449. this command works on Red Hat, but for some reasonn isn't working on kubuntu (latest version).
shell is bash.
i... (3 Replies)
hi gurus.
I have a little script that runs java from a certain directory. This script runs fine when run manually but when I try to schedule it, it fails to find the script.
little_script.sh..
/<directory of java>/java -classpath... (3 Replies)
Hi
I want export input data ...
echo "month: "
read m
export m=$m
also export m is not working ?
the month-variable should be exportet for the use in other scripts,
but it is not working like this. What i'm doing wrong?
Thanks in advance!
IMPe (10 Replies)
Hi All,
I've tried starting syslogd on our hp-ux 11.31 server. However, it is not getting started nor it is updating the syslog file.
There is no space issue also. However, the mail.log file is approx 2GB, can that be of any issue. Please find the details below:
# /sbin/init.d/syslogd... (2 Replies)
Discussion started by: Kits
2 Replies
LEARN ABOUT OSX
for
for(n) Tcl Built-In Commands for(n)
__________________________________________________________________________________________________________________________________________________NAME
for - 'For' loop
SYNOPSIS
for start test next body
_________________________________________________________________DESCRIPTION
For is a looping command, similar in structure to the C for statement. The start, next, and body arguments must be Tcl command strings,
and test is an expression string. The for command first invokes the Tcl interpreter to execute start. Then it repeatedly evaluates test
as an expression; if the result is non-zero it invokes the Tcl interpreter on body, then invokes the Tcl interpreter on next, then repeats
the loop. The command terminates when test evaluates to 0. If a continue command is invoked within body then any remaining commands in
the current execution of body are skipped; processing continues by invoking the Tcl interpreter on next, then evaluating test, and so on.
If a break command is invoked within body or next, then the for command will return immediately. The operation of break and continue are
similar to the corresponding statements in C. For returns an empty string.
Note: test should almost always be enclosed in braces. If not, variable substitutions will be made before the for command starts execut-
ing, which means that variable changes made by the loop body will not be considered in the expression. This is likely to result in an
infinite loop. If test is enclosed in braces, variable substitutions are delayed until the expression is evaluated (before each loop iter-
ation), so changes in the variables will be visible. See below for an example:
EXAMPLES
Print a line for each of the integers from 0 to 10:
for {set x 0} {$x<10} {incr x} {
puts "x is $x"
}
Either loop infinitely or not at all because the expression being evaluated is actually the constant, or even generate an error! The
actual behaviour will depend on whether the variable x exists before the for command is run and whether its value is a value that is less
than or greater than/equal to ten, and this is because the expression will be substituted before the for command is executed.
for {set x 0} $x<10 {incr x} {
puts "x is $x"
}
Print out the powers of two from 1 to 1024:
for {set x 1} {$x<=1024} {set x [expr {$x * 2}]} {
puts "x is $x"
}
SEE ALSO
break, continue, foreach, while
KEYWORDS
for, iteration, looping
Tcl for(n)