2

Details would be appreciated!

I know that it supposed to be a shell script or something like that, but it would be greateful if someone more experienced in this field can tell me more about it.

echo "" >> $HOME/.bashrc && echo "function cdls { cd "$1"; ls --color;}" >> $HOME/.bashrc
3

"echo" will (as the name states) echo a string of text to std out (usually the screen).

">>" will append the output of the preceding command to a file path.

"&&" will run (based on the successful exit of the previous command) the successive command.

";" will run (regardless of the successful exit of the previous command) the successive command.

"function" will create a function that will run in the Bash Shell.

"$HOME" is a reference (Bash Variable) to the user's OS home directory automatically created by Bash.

".bashrc" is a hidden file (in the user's home directory) that is run when the user starts an interactive session. It is often used for customizing the bash shell at the user-level.

"cd" is a directory change, change working directory.

"ls" lists files in the directory. In this case "--color" is an argument that will emphasize certain directory elements with color, rather than using a single color.

"$1" is used to allow a user to pass an argument to this command as a variable.

So, in short, for...

echo "" >> $HOME/.bashrc &&
   echo "function cdls { cd "$1"; ls --color;}" >> $HOME/.bashrc

The first line appends an "empty" line to .bashrc - simply for clarity's sake when someone looks at the file in the future. The second line appends a new function called "cdls" which accepts an argument (a directory name), then changes the working directory to this location, and then immediately runs the "ls" command on this directory.

EDIT: Please see comments from Celada and derobert on steve's answer.

0

Test whether $HOME/.bashrc is writable, by trying to append nothing to it:

echo "" >> $HOME/.bashrc &&

If the test is successful, the file is writable, append a function to it. So that running cdls foo will display a coloured directory listing of directory "foo".

echo "function cdls { cd "$1"; ls --color;}" >> $HOME/.bashrc
  • Will it though? Won't it cd into whatever $1 was expanded to at the time the function was appended to .bashrc? – Celada Apr 10 '17 at 20:18
  • Indeed, the quoting is wrong too: should be cd \"$1\" — or better, the whole thing should be in single quotes, not double quotes, fixing both problems. – derobert Apr 10 '17 at 20:21
  • Also, rather than destructively adding newlines, [[ -w $HOME/.bashrc ]] would probably be a better test. – DopeGhoti Apr 10 '17 at 20:48

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