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Tag: shell

What’s the meaning of a ! before a command in the shell?

What is the purpose of a shell command (part of a shell script) starting with an exclamation mark? Concrete example: In foo.sh: I know that without the space the exclamation mark is used for history replacements and ! <expression> according to the man page can be used to evaluate “True if expr is false”. But in the example context that

“mkdir || echo && exit” exiting even when mkdir succeeds

mkdir $2 || echo “I can’t create directory $2” && exit 8 Hi everyone, this is my first post here, so be kind. I am making a script right now and this line troubles me. The exit 8 should happen only if the directory $2 cannot be created. After running the script and successfully creating that directory, it still exits

Non-dash related bad substitution error

I am trying to write a bash script performing to find and pull somewhere else a specific file type. So far, I came up with the following script: find ./to_compress -type f -iname “*.tar” -mindepth 1 -maxdepth 1 -exec mv {} ./compressed/${{}##*/} However the bash complains that ${{}##*/} is a bad substitution bash: ./compressed/${{}##*/}: bad substitution Some googling around suggested

Extract fields from a custom xml

Im making a script to extract fields from a XML, now i got this and i need to make it work, i was trying with 2 for and greps and i need a little help with this i got this xml withs this fields and i want a output like this for make more comparations: Answer there are many issues

Not able to execute a .csh script using jsch library – Exit 1

Im trying to use Jsch to execute a .csh script on a remote server. I am able to execute commands like cp, mv and ls. But when I try to execute a script that internally references some environment variables, the script is exiting with status 1. There is an INTERNAL_ENV_VARIABLE referenced inside script.sh that is not accessible when i run

Simulate permissions for non-login user

I want to perform some actions on behalf of some non-login users, such as e.g. www-data or uwsgi. My purpose is to test some permissions, check what dirs they can modify etc etc. Is there a recommended way of going about this, other than creating a shell and password for them and su ? edit: When I try to su

get user input in awk script and update it in file

I have a students.txt (RollNo, Name, IDU, CGPA), If Roll number exists prompt the user to change the IDU and CGPA and update the same in the file named “Student.txt” I made the following script: now I need help in taking user input for IDU and CGPA values and update the students.text file with that values against the record found.

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