Bash syntax variable value assignment

Question

I am new to bash scripting. I came across the following piece of code and I am not able to figure it out. Please help me understand.

var1=$var1 some_function_call $var2

var2 is argument to "some_function_call" function.

I am not able to figure out exactly what is going on here. Thanks in advance.

Also any pointer to good bash scripting tutorials would be nice.

Thanks.

wiki.bash-hackers.org/scripting/tutoriallist

Etan Reisner
– Etan Reisner

2015-05-20 01:18:42 +00:00
Commented May 20, 2015 at 1:18 — Etan Reisner
– Etan Reisner, Commented May 20, 2015 at 1:18

Ignacio Vazquez-Abrams · Accepted Answer · 2015-05-20 01:18:18Z

4

The environment of the new some_function_call process has "var1" set to the value of $var1; the environment variable does not change in the main interpreter. The value in $var2 is passed as an argument to some_function_call.

answered May 20, 2015 at 1:18

Ignacio Vazquez-Abrams

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4 Comments

CodeWithPride Over a year ago

there is no 'env' in the code, is 'env' implicit? Meaning is the above code snippet same as env var1=$var1 some_function_call $var2 . From what I understand by your reply, when some_function runs it has the value of 'var1' as set in this piece of code and the value of 'var1' changes only in execution scope of some_function (if var1 was '1' before this function call and var1 is assigned value '2' in this code then var1 is 2 in some_function and 1 otherwise? Please correct me if I am wrong. Thanks

Ignacio Vazquez-Abrams Over a year ago

@CodeWithPride: Yes, except that none of the arguments of env are supported, and there is no intermediate process between the interpreter and some_function_call.

CodeWithPride Over a year ago

What do you mean by "none of the arguments of env are supported". Also, I am unaware of the concept of "intermediate process" in bash. Kindly help in explanation or any links/references where I can understand these things would be very helpful. Thanks.

Ignacio Vazquez-Abrams Over a year ago

env has arguments it takes that changes its behavior; -i, -0, etc. If you use env then bash runs env and then env runs your program, hence env is an intermediate process.

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