[Li|Nux]: braces on the command line
Self-tutoring about Linux: the tutor mentions braces. On the system I use, { Enter will open up a subshell into which you can enter one command per line, as if in a script file. On the last line I just …
Category: Linux
[Li|U]nix: grep part 3: the + operator
Self-tutoring about [Li|U]nix: the tutor continues about grep capabilities. On the system I use, the + (one or more) operator will work with grep if escaped. With the -E option you don’t have to escape it. Therefore, grep “^t\w\+[.]txt” will …
[Li|U]nix: grep, part 2: a bit about character classes
Self-tutoring about Linux and Unix: Can one use Perl’s amazing regex features with grep? Perhaps some of them: the tutor begins… Perl’s convenient \w and \d work with grep, as-is, on the system I use. Frankly, I’m impressed with what …
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[Li|U]nix: grep and grep -E, part1
Self-tutoring about Unix: the tutor continues about grep. After reading my post from yesterday, I was in disbelief. I even tried the command there several more times – it works every time. grep isn’t necessarily expected to support alternation – …
Linux: grep, part 0
Self-tutoring about [Li|U]nix: the tutor begins about grep. grep string filename looks for the string in the file called filename. The string can be a regular expression. In my experience, a regex needs to be quoted. For instance, on the …
[Li|U]nix: “other” characters in file names
Self-tutoring about Unix: the tutor mentions accessing a file name that has non-word characters. Sometimes you’ll look in a directory and you might see a file name such as this(file).txt Yet, if you try to refer to that file in …
[Li|U]nix: awk, part 0
Self-tutoring about Linux: the tutor mentions awk. awk is a utility for getting values from tabulated data. It works line by line. For instance, awk ‘{print $2}’ input.txt will print the second field in each record of input.txt. Source: geeksforgeeks.org
[Li|U]nix: how to get your uid
Self-tutoring about using Linux: the tutor mentions a way to find your own uid. Set a task going such as sleep 360 & & in the command above puts it to the background so you can still run the terminal. …
(Li|U)nix: the dot command
Self-tutoring about (Li|U)nix: the tutor mentions another neat command. The “dot” is just a period. A simple example of the dot command is . file0 If file0 contains Unix commands, they will be executed. Interestingly, with the dot command, file0 …
Linux: tr command
Self-tutoring about Linux: the tutor mentions its neat tr command. tr target replacement is one form of tr, with input being piped to it or redirected to it. For instance, tr “8” “9” < infile.txt will display the file infile.txt …