expr command to extract words

Shell Programming and Scripting
1

how to use expr command to retrieve all the words before the equal sign "=" with shell script

2

expr is not used for that. see the man page for detaild. awk may work for this task.

3

bash substitution

~$ A="fJH DFKGF= ,jfhF"
~$ echo  ${A%=*}
fJH DFKG
4

Here is an example of how to do what you want to do:

$ A="foo=bar"
$ echo $A
foo=bar
$ expr "$A" : '\(.*\)=.*'
foo

From IEEE Std 1003.1:2008

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