Sponsored Content
Full Discussion: Evaluating a variable
Top Forums Shell Programming and Scripting Evaluating a variable Post 302459009 by mikejordan on Sunday 3rd of October 2010 07:26:26 AM
Old 10-03-2010
Evaluating a variable

Does anyone know of a way to force a variable name held in another variable to return the value of the first variable? Best if I give an example, that does not work:
Code:
/usr/local/bin >cat mike.sh
NUM1ref=16
NUM2ref=32
echo "=============="
for VAR in NUM1 NUM2
do
  XXXX=${VAR}ref
  echo $XXXX
  echo "=============="
done
/usr/local/bin >./mike.sh 
==============
NUM1ref
==============
NUM2ref
==============
/usr/local/bin >

I want this to echo the value held in NUM1ref (16), rather than the string "NUM1ref", so the variable XXXX has to be evaluated twice.

I hope that makes sense!

Last edited by Franklin52; 10-03-2010 at 10:33 AM.. Reason: Please indent your code and use code tags
 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

evaluating for a number

I apologize for the simple question but can someone please help me with how to evaluate a number? I will be reading in a file and if a number is >= 100000000, I will do something, if not, I will exit the if statement. Thanks in advance (1 Reply)
Discussion started by: hedrict
1 Replies

2. UNIX for Dummies Questions & Answers

evaluating variables

Hi I have a script in which I have several variables var1 var2 var3 var4 etc...... and field1 field2 field3 field4 etc....... The script similar to this: (6 Replies)
Discussion started by: Bab00shka
6 Replies

3. UNIX for Dummies Questions & Answers

evaluating params

Hi all, I ve a script like.... TBL=employee sql=`cat abhi.sql` \\ abhi.sql contains ------- select a from $TBL echo $TBL echo $sql SQL=`echo $sql` echo $SQL now i want SQL as select a from employee and as select a from $TBL How can I achieve this? Help appriciated (3 Replies)
Discussion started by: abzi
3 Replies

4. Shell Programming and Scripting

* character evaluating too soon - Help!

I have a user defined configuration file, which could contain the following type of entries: directory_001=/a/directory/structure pattern_001=fred* pattern_002=* I have a script which reads the file generically which will loop round loop 1 genvar=”directory” iteration=”001” ... (11 Replies)
Discussion started by: Bab00shka
11 Replies

5. UNIX for Dummies Questions & Answers

evaluating date +%m

how do i evaluate the value of date if ( $(date +%m) > 8 ) then FY_STAMP=FY$(echo $(($(date +%Y) + 1)) | cut -c3-4) else FY_STAMP=FY$(date +%y) fi i want this to make the FY_STAMP increment by 1 if the month is september and up. but cant seem to make it work (3 Replies)
Discussion started by: rsf01
3 Replies

6. Shell Programming and Scripting

Bash: evaluating $? variable (if statement)

Hello, i'm unable to write a correct if... statement to evaluate the $? variable. Could anybody send to me an example? for example, this lines of code didn't work... if ; then etc etc if ; then etc etc Thank you in advanced. (5 Replies)
Discussion started by: aristegui
5 Replies

7. Shell Programming and Scripting

K Shell evaluating value to a variable

Hi, I have the following requirement. V="First" R="V" echo $$R The output should be First. How do i achieve this. how do we evaluate the $R and evaluate it to $V as $R contains V and $V is First. Thanks Vijay (2 Replies)
Discussion started by: vijaykrc
2 Replies

8. Shell Programming and Scripting

$$# is evaluating to 1 when no value

I have the following in my makefile: RESULT=`../${TOOLS_ROOT_PATH}/ext_tools.sh 11`; \ set $$RESULT > tMp; \ rm tMp; \ if ; then \ echo copying external-local tool: $< \($$*\); \ mkdir -p ${EXTERNAL_LOCAL_BIN_DIR}/$<; \ cp -f... (4 Replies)
Discussion started by: jake_ryan
4 Replies

9. Shell Programming and Scripting

evaluating a variable inside a variable

Hi there, i think im getting myself a little confused and need some help :wall: I am reading in a bunch of variables to my script from an external file and need to validate that a value has been set for each so if you can imagine, the user is required to pass in 4 values... (3 Replies)
Discussion started by: rethink
3 Replies

10. UNIX for Dummies Questions & Answers

Parsing file, reading each line to variable, evaluating date/time stamp of each line

So, the beginning of my script will cat & grep a file with the output directed to a new file. The data I have in this file needs to be parsed, read and evaluated. Basically, I need to identify the latest date/time stamp and then calculate whether or not it is within 15 minutes of the current... (1 Reply)
Discussion started by: hynesward
1 Replies
echo(1) 							   User Commands							   echo(1)

NAME
echo - echo arguments SYNOPSIS
/usr/bin/echo [string]... DESCRIPTION
The echo utility writes its arguments, separated by BLANKs and terminated by a NEWLINE, to the standard output. If there are no arguments, only the NEWLINE character is written. echo is useful for producing diagnostics in command files, for sending known data into a pipe, and for displaying the contents of environ- ment variables. The C shell, the Korn shell, and the Bourne shell all have echo built-in commands, which, by default, is invoked if the user calls echo without a full pathname. See shell_builtins(1). sh's echo, ksh's echo, ksh93's echo, and /usr/bin/echo understand the back-slashed escape characters, except that sh's echo does not understand a as the alert character. In addition, ksh's and ksh93's echo does not have an -n option. sh's echo and /usr/bin/echo have an -n option if the SYSV3 environment variable is set (see ENVIRONMENT VARIABLES below). csh's echo and /usr/ucb/echo, on the other hand, have an -n option, but do not understand the back-slashed escape characters. sh and ksh deter- mine whether /usr/ucb/echo is found first in the PATH and, if so, they adapt the behavior of the echo builtin to match /usr/ucb/echo. OPERANDS
The following operand is supported: string A string to be written to standard output. If any operand is "-n", it is treated as a string, not an option. The following char- acter sequences is recognized within any of the arguments: a Alert character.  Backspace. c Print line without new-line. All characters following the c in the argument are ignored. f Form-feed. New-line. Carriage return. Tab. v Vertical tab. \ Backslash. n Where n is the 8-bit character whose ASCII code is the 1-, 2- or 3-digit octal number representing that character. USAGE
Portable applications should not use -n (as the first argument) or escape sequences. The printf(1) utility can be used portably to emulate any of the traditional behaviors of the echo utility as follows: o The Solaris 2.6 operating environment or compatible version's /usr/bin/echo is equivalent to: printf "%b " "$*" o The /usr/ucb/echo is equivalent to: if [ "X$1" = "X-n" ] then shift printf "%s" "$*" else printf "%s " "$*" fi New applications are encouraged to use printf instead of echo. EXAMPLES
Example 1 Finding how far below root your current directory is located You can use echo to determine how many subdirectories below the root directory (/) is your current directory, as follows: o Echo your current-working-directory's full pathname. o Pipe the output through tr to translate the path's embedded slash-characters into space-characters. o Pipe that output through wc -w for a count of the names in your path. example% /usr/bin/echo $PWD | tr '/' ' ' | wc -w See tr(1) and wc(1) for their functionality. Below are the different flavors for echoing a string without a NEWLINE: Example 2 /usr/bin/echo example% /usr/bin/echo "$USER's current directory is $PWDc" Example 3 sh/ksh shells example$ echo "$USER's current directory is $PWDc" Example 4 csh shell example% echo -n "$USER's current directory is $PWD" Example 5 /usr/ucb/echo example% /usr/ucb/echo -n "$USER's current directory is $PWD" ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables that affect the execution of echo: LANG, LC_ALL, LC_CTYPE, LC_MES- SAGES, and NLSPATH. SYSV3 This environment variable is used to provide compatibility with INTERACTIVE UNIX System and SCO UNIX installation scripts. It is intended for compatibility only and should not be used in new scripts. This variable is applicable only for Solaris x86 platforms, not Solaris SPARC systems. EXIT STATUS
The following error values are returned: 0 Successful completion. >0 An error occurred. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ |CSI |Enabled | +-----------------------------+-----------------------------+ |Interface Stability |Committed | +-----------------------------+-----------------------------+ |Standard |See standards(5). | +-----------------------------+-----------------------------+ SEE ALSO
ksh93(1), printf(1), shell_builtins(1), tr(1), wc(1), echo(1B), ascii(5), attributes(5), environ(5), standards(5) NOTES
When representing an 8-bit character by using the escape convention n, the n must always be preceded by the digit zero(0). For example, typing: echo 'WARNING:7' prints the phrase WARNING: and sounds the "bell" on your terminal. The use of single (or double) quotes (or two backslashes) is required to protect the "" that precedes the "07". Following the , up to three digits are used in constructing the octal output character. If, following the n, you want to echo addi- tional digits that are not part of the octal representation, you must use the full 3-digit n. For example, if you want to echo "ESC 7" you must use the three digits "033" rather than just the two digits "33" after the . 2 digits Incorrect: echo "337" | od -xc produces: df0a (hex) 337 (ascii) 3 digits Correct: echo "0337" | od -xc produces: lb37 0a00 (hex) 033 7 (ascii) For the octal equivalents of each character, see ascii(5). SunOS 5.11 8 Apr 2008 echo(1)
All times are GMT -4. The time now is 01:34 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy