ashaarvind
asked on
Korn Shell script problem
I have a strange problem with a Korn shell script running on Digital UNIX v5.1:
for LINE in $(</home/sfdm/arvindk/sfcb
do
echo ${LINE}
done
The file I am reading has:
/home/sfdm/arvindk> cat sfcbom2.txt
[22222B]
If I run this I expect to see [22222B] in output but I see only 2:
/home/sfdm/arvindk> script1
2
On the shell prompt, some numbers work fine but some dont (using \ to escape does work for 32 and 31) -
/home/sfdm/arvindk> echo [44]
[44]
/home/sfdm/arvindk> echo [32]
2
/home/sfdm/arvindk> echo [31]
1
Any idea why this is happening?
Thanks
for LINE in $(</home/sfdm/arvindk/sfcb
do
echo ${LINE}
done
The file I am reading has:
/home/sfdm/arvindk> cat sfcbom2.txt
[22222B]
If I run this I expect to see [22222B] in output but I see only 2:
/home/sfdm/arvindk> script1
2
On the shell prompt, some numbers work fine but some dont (using \ to escape does work for 32 and 31) -
/home/sfdm/arvindk> echo [44]
[44]
/home/sfdm/arvindk> echo [32]
2
/home/sfdm/arvindk> echo [31]
1
Any idea why this is happening?
Thanks
for LINE in `cat /home/sfdm/arvindk/sfcbom2
do
echo $LINE
done
do
echo $LINE
done
ASKER CERTIFIED SOLUTION
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use /usr/bin/echo or wherever you have a echo program instead of the shells built-in echo
also quote the variable (as in ecw's suggestion)
also quote the variable (as in ecw's suggestion)
ASKER
The comment from ecw had the answer. There was a file called '2'in the same directory. It fixed my problem - but I am still puzzled on why this happened?
Thanks/Arvind
Thanks/Arvind
It happened because [ and ] are used by the shell for matching a specfic set of chars during wildcard expansion.
For example
[Aa]* will match all files beginning with an upper or lower case A
[A-Z]* will match all files beginning with an upper case char
*.[aeiou]* will match all files with a . followed by a vowel
The sense of the match is negated if the first char after [ is a ! eg.
*.[!16-9] will match all files that don't end in .1 .6 .7 .8 or .9
Note the use of - to specify a range.
So in your example,
echo ${LINE}
expands to
echo [22222B]
Which is then subject to filename expansion, capable of matching a 'single' character filename of either 2 or B
You just happened to have a file called 2, so it matched that. If you'd also happened to have a file called B, the output would've been
2 B
Sounds like a pencil top me.
For example
[Aa]* will match all files beginning with an upper or lower case A
[A-Z]* will match all files beginning with an upper case char
*.[aeiou]* will match all files with a . followed by a vowel
The sense of the match is negated if the first char after [ is a ! eg.
*.[!16-9] will match all files that don't end in .1 .6 .7 .8 or .9
Note the use of - to specify a range.
So in your example,
echo ${LINE}
expands to
echo [22222B]
Which is then subject to filename expansion, capable of matching a 'single' character filename of either 2 or B
You just happened to have a file called 2, so it matched that. If you'd also happened to have a file called B, the output would've been
2 B
Sounds like a pencil top me.
do
echo $LINE
done