Yes, there is nothing special about the export command it is just another builtin command that also happens update the value of a variable. The real issue is that variable assignments are treated specially by the shell see "Simple Command Expansion" section of the bash manual.
The main bits of concern are :
and
So you see no parameter expansion is done on the text before the = (saved at point 1.).
In contrast the text following the export builtin command gets a full set of tilde, parameter, command and arithmetic expansion: giving us our loophole.
Last edited by Chubler_XL; 02-04-2014 at 02:15 PM..
Reason: clean up formatting
These 2 Users Gave Thanks to Chubler_XL For This Post:
Probably a simple one.
Basically I am retrieving a number from a file - setting a variable against it and then incrementing this by 1 and using this as an entry number in a log file for messages. I need the variable to re-evalute itself each time I call it so I get the latest number in the file -... (1 Reply)
I have variables:
FOO="Text"
BAR="FOO"
I'd like to be able to evaluate the variable named as the value of $BAR.
echo $FOO
Text
echo $BAR
FOO
This is what I'd like to do:
echo ${$BAR} (this won't work)
Text (3 Replies)
Hello,
I have this:
#!/usr/bin/ksh
V1=ABC
str="hello 123;${V1}"
eval "echo $str"
i get
hello 123
/script.sh ABC not found
However eval works if $str variable doesn't contain a semicolumn (eg if str="hello 123~${v1}"
running the eval statement above would produce (2 Replies)
hi,
i'm reading a file "LISTE_FILE" like :
#
$LOGCOM * 5
$PRCCOM * 10
and i want to use the file with "while" and having the fields splitted into new variables for treatment :
while read LINE
do
# Ignorer les commentaires un # en premiere position
if
then... (3 Replies)
How to evaluate the value of a variable ?
For example:
a=var
$a=value !!!error happens!!!
I want to evaluate var=value, how to realize it?
Thanks!
---------- Post updated at 03:37 AM ---------- Previous update was at 02:22 AM ----------
I am using linux bash.
a=var
$a=value... (4 Replies)
I'm writing a script to merge the xkcd webcomic tiles for comic 1110. So far, I have written about 100 lines, and instead of doing each quadrant of the image separately, I've decided to use functions to do this, repeating for every quadrant and using variables for each quadrant to make the function... (9 Replies)
Hi
i tried to execute a below script but it is giving execution error
rec=ABC,1234,55.00
Colno=2
coldel=,
fd='"'$coldel'"'
fprint="'"'{print$'$colno'}'"'"
colsyn=`echo "echo "$rec "| awk -F"$fd $fprint`
echo column syntax is $colsyn
colrec=`colsyn`
echo column is $colrec (5 Replies)
Hi,
I am trying to set a variable that has time the format desired. And my intention is to echo variable (instead of actual date command) everytime I like to echo date. Please take a look at below code.
$NOW=''
echo $NOW
After 5 minutes
$echo $NOW
Issue here is , I am not... (2 Replies)
I want to create a conditional expression string and pass in an awk script. My script is as below...
comm="\$3 == "hello""
awk -F "^T" -v command="${comm}" ' {
if ( command ) { print "hye" }
}' testBut the statement "if ( command )" always evaluates to true which is not... (5 Replies)
I have to display only those subscribers which are in "unconnected state" and the date is 90 days older than today's date.
Below command is used for this purpose:
cat vfsubscriber_20170817.csv | sed -e 's/^"//' -e '1d' | \
nawk -F '",' '{if ( (substr($11,2,4) == 2017) && ( substr($11,2,8)... (1 Reply)
Discussion started by: dia
1 Replies
LEARN ABOUT PHP
shift
shift(1) User Commands shift(1)NAME
shift - shell built-in function to traverse either a shell's argument list or a list of field-separated words
SYNOPSIS
sh
shift [n]
csh
shift [variable]
ksh
* shift [n]
DESCRIPTION
sh
The positional parameters from $n+1 ... are renamed $1 ... . If n is not given, it is assumed to be 1.
csh
The components of argv, or variable, if supplied, are shifted to the left, discarding the first component. It is an error for the variable
not to be set or to have a null value.
ksh
The positional parameters from $n+1 $n+1 ... are renamed $1 ..., default n is 1. The parameter n can be any arithmetic expression that
evaluates to a non-negative number less than or equal to $#.
On this man page, ksh(1) commands that are preceded by one or two * (asterisks) are treated specially in the following ways:
1. Variable assignment lists preceding the command remain in effect when the command completes.
2. I/O redirections are processed after variable assignments.
3. Errors cause a script that contains them to abort.
4. Words, following a command preceded by ** that are in the format of a variable assignment, are expanded with the same rules as a vari-
able assignment. This means that tilde substitution is performed after the = sign and word splitting and file name generation are not
performed.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWcsu |
+-----------------------------+-----------------------------+
SEE ALSO csh(1), ksh(1), sh(1), attributes(5)SunOS 5.10 15 Apr 1994 shift(1)