The real question is not what the region is when the code works or fails, but to what do the expansions of the three shell variables: com_dir, dup_file_name_chk, and save_dir expand when the code works and to what do they expand when it fails. One might guess that it is failing when one of those variables contain one or more whitespace characters. One might also guess that the following would also work:
You haven't told us what shell you're using, but if [[ expression ]] is working and you're running on AIX, I'll assume you are using ksh or bash. The command:
is a shell built-in utility that performs the same parameter expansion and field splitting that happens whenever the shell evaluates a command line. Without the double quotes surrounding the parameter expansions, if there are whitespace characters in the expansions of those variables, field splitting will cause one or both of those tests to fail. It will also fail if $dup_file_name_chk expands to an empty string. but in that case the double bracket test would also fail.
The command:
is part of the syntax of the shell; not a utility. Parameter expansion still occurs in this case, but field splitting does not occur.
These 2 Users Gave Thanks to Don Cragun For This Post:
One of the senior administrators gave me a shell script to modify and it begins as follows:
if ] && ]
{more code follows}
Why the double square brackets? (10 Replies)
Hi,
I just came across an interesting shell script syntax like the one below:
] && (trap 'rm -rf ${WORK_DIR}/*.$$; echo "\n\nInterrupted !!\n\n"; exit 4' 1 2 3 15)
Can someone please explain the code snippet above?
The trap command bit is fine but ] && is the hazy part.
Generally we use an... (2 Replies)
Hello,
Can someone please explain to me the following line,
] && break
I do not understand why two test square brackets are used.
Thanks,
Shantanu
---------- Post updated at 03:38 PM ---------- Previous update was at 03:35 PM ----------
And, also why there's a $ before (echo $c |... (5 Replies)
hi guys,
i'm writing a script that looks for a unquie id in a file and replaces a string between two square brackets on the same line as the unquie id:
.......
.......
0001 zz 43242 replace this text] name
0002 sd 65466 UK] country
.......
.......
how can i find line with id 0001... (6 Replies)
Hi All,
I have a text file which looks like this:
computer programming
systems engineering
I want to get rid of these square brackets and also the text that is inside these brackets. So that my final text file looks like this:
computer programming
systems engineering
I am using... (3 Replies)
Hi All,
After searching about this, I could find some solutions but I am not sure why it is not working in my case.
I have a text file with contents between two square brackets. The text file looks like this:
Use tags when you post any code so others can easily read your code. You can... (2 Replies)
Hi frieds, I don't understand the difference between single square bracket and double square brackets in a IF condition.
Ex.
if ;
then
RETURNJOB=1
else
RETURNJOB=0
fi
It run, but this
if ];
then
RETURNJOB=1
else
RETURNJOB=0
fi (4 Replies)
I wanted to store the number inside the square bracket between colon( : ) and closing suqre bracket(]) in some variable.
Suppose I have lines like :
Input file :
20140320 00:08:23.846 INFO 84] - anything in line
20140320 00:08:23.846 Test 589] - Virtual and lab lab anything... (18 Replies)
Hello all,
I have the following problem:
$ cat infile
this is spam and i need this too
this is spam and i need this too
$ perl -nwe '$_ =~ /]+ \]+)\]\]*\]? (\+)$/; print "$1 - $2\n";' infile
i need this - too
i need this - and i need this too
I am not sure how many occurences of... (13 Replies)
Discussion started by: zaxxon
13 Replies
LEARN ABOUT SUSE
funcombine
funcombine(7) SAORD Documentation funcombine(7)NAME
FunCombine - Combining Region and Table Filters
SYNOPSIS
This document discusses the conventions for combining region and table filters, especially with regards to the comma operator.
DESCRIPTION
Comma Conventions
Filter specifications consist of a series of boolean expressions, separated by commas. These expressions can be table filters, spatial
region filters, or combinations thereof. Unfortunately, common usage requires that the comma operator must act differently in different
situations. Therefore, while its use is intuitive in most cases, commas can be a source of confusion.
According to long-standing usage in IRAF, when a comma separates two table filters, it takes on the meaning of a boolean and. Thus:
foo.fits[pha==1,pi==2]
is equivalent to:
foo.fits[pha==1 && pi==2]
When a comma separates two spatial region filters, however, it has traditionally taken on the meaning of a boolean or. Thus:
foo.fits[circle(10,10,3),ellipse(20,20,8,5)]
is equivalent to:
foo.fits[circle(10,10,3) || ellipse(20,20,8,5)]
(except that in the former case, each region is given a unique id in programs such as funcnts).
Region and table filters can be combined:
foo.fits[circle(10,10,3),pi=1:5]
or even:
foo.fits[pha==1&&circle(10,10,3),pi==2&&ellipse(20,20,8,5)]
In these cases, it is not obvious whether the command should utilize an or or and operator. We therefore arbitrarily chose to implement the
following rule:
o if both expressions contain a region, the operator used is or.
o if one (or both) expression(s) does not contain a region, the operator used is and.
This rule handles the cases of pure regions and pure column filters properly. It unambiguously assigns the boolean and to all mixed cases.
Thus:
foo.fits[circle(10,10,3),pi=1:5]
and
foo.fits[pi=1:5,circle(10,10,3)]
both are equivalent to:
foo.fits[circle(10,10,3) && pi=1:5]
[NB: This arbitrary rule replaces the previous arbitrary rule (pre-funtools 1.2.3) which stated:
o if the 2nd expression contains a region, the operator used is or.
o if the 2nd expression does not contain a region, the operator used is and.
In that scenario, the or operator was implied by:
pha==4,circle 5 5 1
while the and operator was implied by
circle 5 5 1,pha==4
Experience showed that this non-commutative treatment of the comma operator was confusing and led to unexpected results.]
The comma rule must be considered provisional: comments and complaints are welcome to help clarify the matter. Better still, we recommend
that the comma operator be avoided in such cases in favor of an explicit boolean operator.
SEE ALSO
See funtools(7) for a list of Funtools help pages
version 1.4.2 January 2, 2008 funcombine(7)