Sponsored Content
Full Discussion: Conditions in if
Top Forums Shell Programming and Scripting Conditions in if Post 302840513 by Don Cragun on Monday 5th of August 2013 08:56:50 PM
Old 08-05-2013
I strongly suggest using something like getopts when parsing command line arguments. When you use getopts to process options, you get the same capabilities all of the standard utilities use when parsing options: single-character options without option-arguments can be grouped behind a single minus sign or each can follow separate minus signs, options with option-arguments can be combined in a single operand or be presented as separate arguments, -- can be used to end option processing so following operands can start with a minus sign and not be mistaken for options, the order of options won't matter, etc.

From your example, it appeared that you code script could be invoked as:
./script, ./script -k, or ./script -f file. The following can be invoked with no options, with -k or -f file, or with both -k and -f file in any order. When the -f option is given, this script gives an error if the option argument is not a regular file. if you call this script with options other than -f and -k, it will tell you that it found an option it didn't expect. It also tells you how many operands are left after the options are processed and prints them.

Hope this helps:
Code:
#!/bin/ksh
IAm=${0##*/}
err=0
File=""
kflag=
while getopts f:k opt
do      case $opt in
        (f)     File="$OPTARG"
                if [ ! -f "$File" ]
                then    printf "Option -f \"%s\": Not a regular file\n" "$File" >&2
                        err=1
                fi;;
        (k)     kflag=1;;
        (?)     err=2;;
        esac
done
shift $(($OPTIND - 1))
if [ $err -gt 0 ]
then    printf "Usage: %s: [-k] [-f pathname] arg...\n" "$IAm" >&2
        exit $err
fi
if [ "$kflag" ]
then    printf "Option −k found\n"
fi
if [ -n "$File" ]
then    printf "Option -f \"%s\" found; argument is a regular file\n" "$File"
fi
if [ $# -gt 0 ]
then    printf "%d remaining operands are:" $#
        printf " %s" "$*"
        echo
else    echo "No operands found."
fi


Last edited by Don Cragun; 08-05-2013 at 09:58 PM.. Reason: Add missing <newline>...
 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

2 or more if conditions

Hello, I have a file as follows: col no:1 2 3 4 5 6 7 8 9 10 11 a 4 226 226 ch:95024048-95027592, 1y224 of 3545 223 224 ident b 53 235 235 ch:148398-148401255, 1y184 of 3187 180 186 ident awk... (3 Replies)
Discussion started by: dr_sabz
3 Replies

2. Shell Programming and Scripting

multiple if conditions

Guys, Im trying to have a script that evaluates multiple conditions : test.sh: if then echo "host $1" else if then echo "host $1" else echo $1 not valid exit 1 fi when I do ./test.sh brazil1 I get: (4 Replies)
Discussion started by: bashshadow1979
4 Replies

3. Shell Programming and Scripting

conditions

./script 89 The script will extract the last digit of the input parameter. example, that is 4. This will be compared to the last digit of the current day of the month ( like day 14; that is 4). A message will displayed on the screen indicating if the digits are the same or not. (1 Reply)
Discussion started by: singh is king
1 Replies

4. Shell Programming and Scripting

Help regarding multiple conditions

Hi All, I am new to shell scripting. Can any one say what is wrong in this if statement, that uses multiple conditions if then *************** else if ( -z $pcs && "$night_time_calc" > "$night_time" ) then ******************************** ... (4 Replies)
Discussion started by: ssenthilkumar
4 Replies

5. Shell Programming and Scripting

While with three conditions

Currently this is what I am trying while || && ]; do I want to continue if the first condition or both the second and third are true but I am getting a too many arguments error. Can someone help me out? (5 Replies)
Discussion started by: whdr02
5 Replies

6. Shell Programming and Scripting

IF OR with two conditions

I have this IF working fine, testing if a char is a digit: if ; then _VALUE=$_VALUE$_CHAR else _ISDIGIT="false" fi Then I add a second condition to test if the char is either a digit or a * if ]; then _VALUE=$_VALUE$_CHAR ... (11 Replies)
Discussion started by: Flavius
11 Replies

7. Shell Programming and Scripting

If conditions need

Dear Expert, Below code is for to take the backup of database by daily time stamp. I need vital help to make my script automatic sending me email if it sucess or fail. echo on @REM Seamonkey's quick date batch (MMDDYYYY format) @REM Setups %date variable @REM First parses month, day, and... (6 Replies)
Discussion started by: Alone
6 Replies

8. Shell Programming and Scripting

Zenity, While, and Conditions

All, I'm having fighting a losing battle with what I though would be simple. My goal is this: Show a zenity progress or info dialog until the system obtains an ip address, then close the dialog and continue through the rest of the script. Right now I've got the following: ip=`ifconfig |... (2 Replies)
Discussion started by: timbrammer91091
2 Replies

9. Shell Programming and Scripting

Errors in if conditions with to many OR conditions

Hi ALL I have a script where in i need to check for several values in if conditons but when i execute the script it throws error such as "TOO MANY ARGUMENTS" if then msg="BM VAR Issue :: bmaRequestVAR=$bmaRequestVAR , nltBMVAR=$nltBMVAR , bmaResponseVAR=$bmaResponseVAR ,... (10 Replies)
Discussion started by: nikhil jain
10 Replies

10. Shell Programming and Scripting

Errors in if conditions.....

#if if then echo $varNO >> AgriN.csv fi done < data The above script throws error such as integer expression expected. How do i rectify that?? (4 Replies)
Discussion started by: nikhil jain
4 Replies
getoptcvt(1)							   User Commands						      getoptcvt(1)

NAME
getoptcvt - convert to getopts to parse command options SYNOPSIS
/usr/lib/getoptcvt [-b] filename /usr/lib/getoptcvt DESCRIPTION
/usr/lib/getoptcvt reads the shell script in filename, converts it to use getopts instead of getopt, and writes the results on the standard output. getopts is a built-in Bourne shell command used to parse positional parameters and to check for valid options. See sh(1). It supports all applicable rules of the command syntax standard (see Rules 3-10, Intro(1)). It should be used in place of the getopt command. (See the NOTES section below.) The syntax for the shell's built-in getopts command is: getopts optstring name [ argument...] optstring must contain the option letters the command using getopts will recognize; if a letter is followed by a colon (:), the option is expected to have an argument, or group of arguments, which must be separated from it by white space. Each time it is invoked, getopts places the next option in the shell variable name and the index of the next argument to be processed in the shell variable OPTIND. Whenever the shell or a shell script is invoked, OPTIND is initialized to 1. When an option requires an option-argument, getopts places it in the shell variable OPTARG. If an illegal option is encountered, ? will be placed in name. When the end of options is encountered, getopts exits with a non-zero exit status. The special option -- may be used to delimit the end of the options. By default, getopts parses the positional parameters. If extra arguments (argument ...) are given on the getopts command line, getopts parses them instead. So that all new commands will adhere to the command syntax standard described in Intro(1), they should use getopts or getopt to parse posi- tional parameters and check for options that are valid for that command (see the NOTES section below). OPTIONS
The following option is supported: -b Makes the converted script portable to earlier releases of the UNIX system. /usr/lib/getoptcvt modifies the shell script in filename so that when the resulting shell script is executed, it determines at run time whether to invoke getopts or getopt. EXAMPLES
Example 1 Processing the arguments for a command The following fragment of a shell program shows how one might process the arguments for a command that can take the options -a or -b, as well as the option -o, which requires an option-argument: while getopts abo: c do case $c in a | b) FLAG=$c;; o) OARG=$OPTARG;; ?) echo $USAGE exit 2;; esac done shift `expr $OPTIND - 1` Example 2 Equivalent code expressions This code accepts any of the following as equivalent: cmd -a -b -o "xxx z yy" filename cmd -a -b -o "xxx z yy" -filename cmd -ab -o xxx,z,yy filename cmd -ab -o "xxx z yy" filename cmd -o xxx,z,yy b a filename ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables that affect the execution of getopts: LC_CTYPE, LC_MESSAGES, and NLSPATH. OPTIND This variable is used by getoptcvt as the index of the next argument to be processed. OPTARG This variable is used by getoptcvt to store the argument if an option is using arguments. EXIT STATUS
The following exit values are returned: 0 An option, specified or unspecified by optstring, was found. >0 The end of options was encountered or an error occurred. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | |CSI |enabled | +-----------------------------+-----------------------------+ SEE ALSO
Intro(1), getopts(1), sh(1), shell_builtins(1), getopt(3C), attributes(5) DIAGNOSTICS
getopts prints an error message on the standard error when it encounters an option letter not included in optstring. NOTES
Although the following command syntax rule (see Intro(1)) relaxations are permitted under the current implementation, they should not be used because they may not be supported in future releases of the system. As in the EXAMPLES section above, -a and -b are options, and the option -o requires an option-argument. The following example violates Rule 5: options with option-arguments must not be grouped with other options: example% cmd -aboxxx filename The following example violates Rule 6: there must be white space after an option that takes an option-argument: example% cmd -ab oxxx filename Changing the value of the shell variable OPTIND or parsing different sets of arguments may lead to unexpected results. SunOS 5.11 7 Jan 2000 getoptcvt(1)
All times are GMT -4. The time now is 02:50 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy