I wrote this answer down because I thought this would be a fun (and fitting) analogy: Think of a lockable object as a blackboard (lockable) in a class room containing a teacher (writer) and many students (readers). While a teacher is writing something (exclusive lock) on the board: Nobody can read it, because it’s still … Read more
As grawity said, ~/.bashrc is what you want, since it is sourced by non-interactive non-login shells. I expect the problem you’re having has to do with the default Ubuntu ~/.bashrc file. It usually starts with something like this: # If not running interactively, don’t do anything [ -z “$PS1” ] && return You want to … Read more
The command you have to use is not diff but comm comm -23 a.txt b.txt By default, comm outputs 3 columns: left-only, right-only, both. The -1, -2 and -3 switches suppress these columns. So, -23 hides the right-only and both columns, showing the lines that appear only in the first (left) file. If you want … Read more
as simple as: find . -mtime -1 | xargs tar –no-recursion -czf myfile.tgz where find . -mtime -1 will select all the files in (recursively) current directory modified day before. you can use fractions, for example: find . -mtime -1.5 | xargs tar –no-recursion -czf myfile.tgz
Both signals are designed to suspend a process which will be eventually resumed with SIGCONT. The main differences between them are: SIGSTOP is a signal sent programmatically (eg: kill -STOP pid ) while SIGTSTP (for signal – terminal stop) may also be sent through the tty driver by a user typing on a keyboard, usually … Read more
(head -n 2 <file> && tail -n +3 <file> | sort) > newfile The parentheses create a subshell, wrapping up the stdout so you can pipe it or redirect it as if it had come from a single command.
Use the fact that awk splits the lines in fields based on a field separator, that you can define. Hence, defining the field separator to / you can say: awk -F “https://stackoverflow.com/” ‘{print $NF}’ input as NF refers to the number of fields of the current record, printing $NF means printing the last one. So … Read more
The man pages is the best source of information you can find… and is at your fingertips: man mkdir yields this about -p switch: -p, –parents no error if existing, make parent directories as needed Use case example: Assume I want to create directories hello/goodbye but none exist: $mkdir hello/goodbye mkdir:cannot create directory ‘hello/goodbye’: No … Read more
I’ll have a go at this. To delete 5 lines after a pattern (including the line with the pattern): sed -e ‘/pattern/,+5d’ file.txt To delete 5 lines after a pattern (excluding the line with the pattern): sed -e ‘/pattern/{n;N;N;N;N;d}’ file.txt
Brace expansion, {x..y} is performed before other expansions, so you cannot use that for variable length sequences. Instead, use the seq 2 $max method as user mob stated. So, for your example it would be: max=10 for i in `seq 2 $max` do echo “$i” done