CODEWITHSUNDEEP
shellunix
Raj
Raj

Reputation: 4462

what does '$?' mean in a shell script?

I came across a shell script that contains a statement like,

if [ $val -eq $? ]

What does $? mean here?

Upvotes: 15

Views: 110996

Answers (6)

biolinh
biolinh

Reputation: 2225

I found that the link is very useful and is the great answer. It includes clearly expression with sample.

enter image description here

Upvotes: 26

sreevathsa r
sreevathsa r

Reputation: 1

ls *.* or ls would produce the same result. Meaning show zero or more files with any extension in the current directory.

echo $? would display the exit status. If at least one file is displayed from the last command ,the exit status would be zero(success).

Upvotes: -1

nickleefly
nickleefly

Reputation: 3753

$# = number of arguments. Answer is 3.

$@ = what parameters were passed. Answer is 1 2 3.

$? = was last command successful. Answer is 0 which means 'yes'.

Upvotes: 17

donald123
donald123

Reputation: 5749

What does $? mean here?

$? is the last result of an exit-status ... 0 is by default "successfull"

bash# ls *.*
bash# echo $? 
bash# 0
bash# ls /tmp/not/existing/
bash# echo $?
bash# 2

Upvotes: 3

noobed
noobed

Reputation: 1339

$?

returns the status of the last finished command. Status 0 tells you that everything finished ok.

In addition the $ sign is a special symbol - and in that case $val extract the value that is hold by the variable val

Upvotes: 22

mouviciel
mouviciel

Reputation: 67859

This is the value of the exit status of the previous command. This is 0 in case of success.

Upvotes: 2

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