FAQ - ba$h0

Frequently asked questions

I’m lost in the terminal

Use the command pwd to know in which directory you are.
Use ls to read the file and directory contents.
Use cd to go back to your home.

Navigate in the terminal and history

command	result
→ or ←	Use the arrows to change the prompt position
↑ or ↓	Navigate in the commands you already wrote
`ctrl` + `r`	Search in the history of commands
`history`	Print to the screen the last x command lines

Frequent error messages:

Generally, the errors in the terminal are clear and helpful. If you don’t understand them:

Ask a collegue for help
Ask and look on the internet (i.e. StackOverflow)
Ask on Framateam

⮕ No such file or directory

my.name@cluster-i2bc:~$ ls coursBash
ls: cannot access 'coursBash': No such file or directory

Here ls can’t find any directory or file with this name :

I made a mistake when I wrote the file name: use <TAB><TAB> while writing to avoid this
I am not in the write directory: check with pwd or use find to search in file system

⮕ Unrecognized option

my.name@cluster-i2bc:~$ ls --alls
ls: unrecognized option '--alls'
Try 'ls --help' for more information.

I made a mistake when I wrote the option name: check the manual with ls --help or man ls
Did I use the write version of the tool (maybe this option doesn’t exist in the current one): ls --version

⮕ Command not found

my.name@cluster-i2bc:~$ ls-l
-bash: ls-l: command not found

The bash terminal is looking for the command ls-l that it can’t find:

I made a mistake by writing the command: use <TAB><TAB> to avoid this
I forgot a space between the command and the options
The tool is not installed or not loaded: module, conda…

⮕ Permission denied

my.name@cluster-i2bc:~$ rm diff-counts.tsv.gz
rm: remove write-protected regular file 'diff-counts.tsv.gz'? y
rm: cannot remove 'diff-counts.tsv.gz': Permission denied

I want to remove a file but bash is not allowing me to do this:

How to check permission: ls -l
How to check the owner: whoami associated with ls -l

⮕ Know if a command ended correctly

I want to know if my command ended correctly, is that possible? Yes with $?

my.name@cluster-i2bc:~$ ls -l
total 116
-rw-r--r-- 1 root root 14932 Jan 18  2018 diff-counts.tsv.gz
my.name@cluster-i2bc:~$ echo $?
0
my.name@cluster-i2bc:~$ ls-l
-bash: ls-l: command not found
my.name@cluster-i2bc:~$ echo $?
127

When the command executes correctly, bash returns an error value of 0 (=no error), but when an error occurs the value is different from 0 (in the exemple, the value is 127).

`~` or `|` on MAC

~ = option + N or Alt + N

| = Alt + Shift + L