Unix null string

Quick Links. Search Forums. Show Threads. Show Posts. Shell Programming and Scripting. How to check for null or empty string. Registered User. Join Date: Jul Please modify this script Code :. Last edited by Yogesh Sawant; at AM.. Reason: added code tags. Join Date: Dec Please read our rules and refrain from bumping your posts.

Thanks, ZB. Originally Posted by zazzybob. You shuld post the solution to help other forum members having same type of problems in coming future Cheers, Awadhesh. Originally Posted by doer. Code :. Parsing null or empty output. I am working an some if then statements for a script. Join Date: Apr You can try something like this : Code :. Join Date: Feb Originally Posted by misenkiser. Code :. In all the responses it has been assumed that the position will be the last portion in the file however the line length may be upto 80 chars whereas the search should be only for position.

Python alternative: Code :. Check for not null column in a pipe delimited file. Hi, I have a requirement where I have to check whether the mandatory columns in a pipe delimited file is null and print error message. The data file will have aroung , Check file for string existence before appending it with string. I want to append file with a string but before doing that i want to check if this string already exist in that file.

I tried with grep on Solaris 10 but unsuccessful. Man pages from grep seems to suggest if the string is found command status will be 0 and if not 1. But i am not finding it. May be i If either is NULL then pgm should quit. I wrote the following: bash Check for null. From the question's title, this appears to be the distinction you are trying to make, but it is unclear from the question if indeed you care or are even aware of this distinction.

Do you care about that distinction? If so test -z will not help. Add a comment. Active Oldest Votes. Improve this answer. It can be more clear for the one reading the code that you want to see if the var is empty. I would leave the string comparison for the cases in which you are comparing with a non-empty string. Chock if a variable is set! I much prefer the -n.