Function needs to be called based on its first character in a supplied string Post: 303037127

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Top Forums UNIX for Beginners Questions & Answers Function needs to be called based on its first character in a supplied string Post 303037127 by drysdalk on Wednesday 24th of July 2019 08:33:54 AM

07-24-2019

Registered User

Hi,

Assuming you're using Bash as your shell, this is the ideal situation for the case statement. Consider the following example:

Code:

$ cat data.txt
Jog
mog
cat
dog
jug
Man
$ cat script.sh
#!/bin/bash

function j
{
        echo "Function J has been called with the following parameter: $1"
        return
}

function m
{
        echo "Function M has been called with the following parameter: $1"
        return
}

while read parameter
do
        echo "Considering parameter "$parameter"..."

        case "$parameter" in
                J*|j*)
                        j "$parameter"
                        ;;
                M*|m*)
                        m "$parameter"
                        ;;
        esac
done < data.txt

$ ./script.sh
Considering parameter Jog...
Function J has been called with the following parameter: Jog
Considering parameter mog...
Function M has been called with the following parameter: mog
Considering parameter cat...
Considering parameter dog...
Considering parameter jug...
Function J has been called with the following parameter: jug
Considering parameter Man...
Function M has been called with the following parameter: Man
$

Here the script reads all the parameters one at a time from the file data.txt, and if they start with a lower- or upper-case J or M the appropriate function is called. If the parameter under consideration starts with any other character whatsoever, no function is called, and the script moves right on to the next parameter in the file, continuing in this manner until it reaches the end.

Hope this helps !

drysdalk

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LEARN ABOUT LINUX

rbash

RBASH(1)						      General Commands Manual							  RBASH(1)

NAME

       rbash - restricted bash, see bash(1)

RESTRICTED SHELL

       If  bash  is  started with the name rbash, or the -r option is supplied at invocation, the shell becomes restricted.  A restricted shell is
       used to set up an environment more controlled than the standard shell.  It behaves identically to bash with the exception that the  follow-
       ing are disallowed or not performed:

       o      changing directories with cd

       o      setting or unsetting the values of SHELL, PATH, ENV, or BASH_ENV

       o      specifying command names containing /

       o      specifying a file name containing a / as an argument to the .  builtin command

       o      specifying a filename containing a slash as an argument to the -p option to the hash builtin command

       o      importing function definitions from the shell environment at startup

       o      parsing the value of SHELLOPTS from the shell environment at startup

       o      redirecting output using the >, >|, <>, >&, &>, and >> redirection operators

       o      using the exec builtin command to replace the shell with another command

       o      adding or deleting builtin commands with the -f and -d options to the enable builtin command

       o      using the enable builtin command to enable disabled shell builtins

       o      specifying the -p option to the command builtin command

       o      turning off restricted mode with set +r or set +o restricted.

       These restrictions are enforced after any startup files are read.

       When a command that is found to be a shell script is executed, rbash turns off any restrictions in the shell spawned to execute the script.

SEE ALSO

       bash(1)

GNU Bash-4.0							    2004 Apr 20 							  RBASH(1)

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