Tanguy Lefort

Tanguy Lefort

PhD Student in statistics

Bash and other shell commands

Some shell commands that can be useful sometimes and keep spending too much time to find back. For some commands I put the Windows equivalent (might be handy when not on your own machine).

Regexp: everything seems easier after that

  • General placements
^           #beginning of a line
$           #end of a line
*           #anything
  • Occurrences for a character
x*         #x appears at least zero times
x+         #x appears at least once
x?         #x is facultative
x{4}       #a sequence of 4 x
x{2,4}     #x apppears 2, 3 or 4 times
\.         #match the . character
  • Class of characters
[a-z]     #all lower cases letters
[Aa]bc    #abc with or without upper case for a
[^0-9]    #anything but numbers
  • The alternative
mi[n|m]e  #match the words mime and mine
you|me|her #match any of the three

Basics

  • Move around
cd <path>  #go to <path>
cd ..      #go up in the tree structure
cd ~       #go home
cd         #go home
pwd        #print working directory
  • Remove files (recursively) Be very careful with that one!
rm -r
  • Show files in a directory
ls
ls -a #show hidden files too
ls -l #show accesses and sizes
  • Get help
man <fctn>
  • Search commands
grep <regexp> <path>

The -C flags show the number of the lines, -c counts the number of lines, -l the name of the files containing the chain of characters.

find <path> <criteria> -print #find files matching the criteria

Some flags are -name, -size or -mtime (last modified). To combine some criterions use \(<match1> -o <match2>\) it’s the logical or.

ls -1 | wc -l #number of files in repository
  • Create something new
mkir <name> #new repository
touch <name> #new empty file if doesn't exist

The touch command, when used on a pre-existing file, updates the time/date stamp.

  • See the content
cat <file> #display the content
vi <file>  #open the default terminal editor, :q to exit
  • Locate the executable (eg python…)
which <executable>
  • Unzip folder
tar -xvf <file>.tar
tar zxvf <file>.tar.gz
unzip <file>.zip -d <directory>

With unzip, use -o to overwrite.

  • Some Windows equivalents For some commands, Unix and Windows are the same. Just try and/or Google it (especially don’t try if it might be dangerous).
cd        #print working directory when on its own
deltree   #delete recursively
dir /ah   #show files
help      #get help
find      #equivalent of grep
tree | find <tomatch> #equivalent of unix find
edit      #equivalent of vi
where     #equivalent of which

Environment variables

  • Add one
export NAME=VALUE

This can be done in the shell, or in ~/.bashrc.

  • Reload the .bashrc
source ~/.bashrc
  • See variables in PATH
echo $PATH

Some SSH

  • Send from local to remote
scp <path_to_file> <login>@<server>:<directory>

Use the -r flag for recursivity. If there is an error like is a directory it means it isn’t a directory, so use mkdir and then try again.

  • Send from remote to local
scp <login>@<server>:<path_to_file> <directory>

To transfer files, rsync is worth looking.

  • Download from URL
wget <url>
  • Chronometer (when you don’t have your phone at arms length)
date1=`date +%s`; while true; do echo -ne "$(date -u --date @$((`date +%s` - $date1)) +%H:%M:%S)\r"; done
  • Display time
timedatectl #a lot of infos
date + "%d-%m-%y" #date with a format
date --date='23 Nov' +%u #which week day for my birthday?
  • In Windows
date
time
  • Info on the GPU hardware
lspci | grep -i --color 'vga\|3d\|2d'
  • Cuda version and GPU status
nvidia-smi

Visualize site locally

bundle-2.7 exec jekyll clean  #clean slate
bundle-2.7 exec jekyll serve  #make it available locally

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