ZSH as Alternative Shell

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The ZSH, short for z-shell, is an alternative shell for Linux that offers many convenience features for productive use that bash, the default shell, does not offer.

This should be a short introduction to zsh and offer some examples that are especially useful on ZIH systems.

oh-my-zsh

oh-my-zsh is a plugin that adds many features to the zsh with a very simple install. Simply run:

marie@login$ sh -c "$(curl -fsSL https://raw.githubusercontent.com/ohmyzsh/ohmyzsh/master/tools/install.sh)"

and then, if it is not already your login shell, run zsh or re-login.

The rest of this document assumes that you have oh-my-zsh installed and running.

Features

Themes

There are many different themes for the zsh. See the GitHub-page of oh-my-zsh for more details.

Auto-completion

zsh offers more auto-completion features than bash. You can auto-complete programs, filenames, parameters, man-pages and a lot more, and you can cycle through the suggestions with TAB-button.

Syntax-highlighting

When you add this line to your ~/.zshrc with oh-my-zsh installed, you get syntax-highlighting directly in the shell:

plugins+=(
  zsh-syntax-highlighting
)

Typo-correction

With

setopt correct_all
ENABLE_CORRECTION="true"

in ~/.zshrc you get correction suggestions when the shell thinks that it might be what you want, e.g. when a command is expected to be handed an existing file.

Automatic cd

Adding AUTO_CD to ~/.zshrc file allows to leave out the cd when a folder name is provided.

setopt AUTO_CD

fish-like auto-suggestions

Install zsh-autosuggestions to get fish-shell-like auto-suggestions of previous commands that start with the same letters and that you can complete with the right arrow key.

Addons for your shell

bashzsh

# Create a new directory and directly `cd` into it
mcd () {
    mkdir -p $1
    cd $1
}

# Find the largest files in the current directory easily
function treesizethis {
    du -k --max-depth=1 | sort -nr | awk '
     BEGIN {
    split("KB,MB,GB,TB", Units, ",");
     }
     {
    u = 1;
    while ($1 >= 1024) {
       $1 = $1 / 1024;
       u += 1
    }
    $1 = sprintf("%.1f %s", $1, Units[u]);
    print $0;
     }
    '
}

#This allows you to run `slurmlogpath $SLURM_ID` and get the log-path directly in stdout:
function slurmlogpath {
    scontrol show job $1 | sed -n -e 's/^\s*StdOut=//p'
}

# `ftails` follow-tails a slurm-log. Call it without parameters to tail the only running job or
# get a list of running jobs or use `ftails $JOBID` to tail a specific job
function ftails {
    JOBID=$1
    if [[ -z $JOBID ]]; then
         JOBS=$(squeue --format="%i \\'%j\\' " --me | grep -v JOBID)
         NUMBER_OF_JOBS=$(echo "$JOBS" | wc -l)
         JOBID=
         if [[ "$NUMBER_OF_JOBS" -eq 1 ]]; then
             JOBID=$(echo $JOBS | sed -e "s/'//g" | sed -e 's/ .*//')
         else
             JOBS=$(echo $JOBS | tr -d '\n')
             JOBID=$(eval "whiptail --title 'Choose jobs to tail' --menu 'Choose Job to tail' 25 78 16 $JOBS" 3>&1 1>&2 2>&3)
         fi
    fi
    SLURMLOGPATH=$(slurmlogpath $JOBID)
    if [[ -e $SLURMLOGPATH ]]; then
        tail -n100 -f $SLURMLOGPATH
    else
        echo "No slurm-log-file found"
    fi
}

#With this, you only need to type `sq` instead of `squeue -u $USER`.
alias sq="squeue --me"

# Create a new directory and directly `cd` into it
mcd () {
    mkdir -p $1
    cd $1
}

# Find the largest files in the current directory easily
function treesizethis {
    du -k --max-depth=1 | sort -nr | awk '
     BEGIN {
    split("KB,MB,GB,TB", Units, ",");
     }
     {
    u = 1;
    while ($1 >= 1024) {
       $1 = $1 / 1024;
       u += 1
    }
    $1 = sprintf("%.1f %s", $1, Units[u]);
    print $0;
     }
    '
}

#This allows you to run `slurmlogpath $SLURM_ID` and get the log-path directly in stdout:
function slurmlogpath {
    scontrol show job $1 | sed -n -e 's/^\s*StdOut=//p'
}

# `ftails` follow-tails a slurm-log. Call it without parameters to tail the only running job or
# get a list of running jobs or use `ftails $JOBID` to tail a specific job
function ftails {
    JOBID=$1
    if [[ -z $JOBID ]]; then
         JOBS=$(squeue --format="%i \\'%j\\' " --me | grep -v JOBID)
         NUMBER_OF_JOBS=$(echo "$JOBS" | wc -l)
         JOBID=
         if [[ "$NUMBER_OF_JOBS" -eq 1 ]]; then
             JOBID=$(echo $JOBS | sed -e "s/'//g" | sed -e 's/ .*//')
         else
             JOBS=$(echo $JOBS | tr -d '\n')
             JOBID=$(eval "whiptail --title 'Choose jobs to tail' --menu 'Choose Job to tail' 25 78 16 $JOBS" 3>&1 1>&2 2>&3)
         fi
    fi
    SLURMLOGPATH=$(slurmlogpath $JOBID)
    if [[ -e $SLURMLOGPATH ]]; then
        tail -n100 -f $SLURMLOGPATH
    else
        echo "No slurm-log-file found"
    fi
}

#With this, you only need to type `sq` instead of `squeue -u $USER`.
alias sq="squeue --me"

#This will automatically replace `...` with `../..` and `....` with `../../..`
# and so on (each additional `.` adding another `/..`) when typing commands:
rationalise-dot() {
    if [[ $LBUFFER = *.. ]]; then
        LBUFFER+=/..
    else
        LBUFFER+=.
    fi
}
zle -N rationalise-dot
bindkey . rationalise-dot

# This allows auto-completion for `module load`:
function _module {
    MODULE_COMMANDS=(
        '-t:Show computer parsable output'
        'load:Load a module'
        'unload:Unload a module'
        'spider:Search for a module'
        'avail:Show available modules'
        'list:List loaded modules'
    )

    MODULE_COMMANDS_STR=$(printf "\n'%s'" "${MODULE_COMMANDS[@]}")

    eval "_describe 'command' \"($MODULE_COMMANDS_STR)\""
    _values -s ' ' 'flags' $(ml -t avail | sed -e 's#/$##' | tr '\n' ' ')
}

compdef _module "module"

Setting zsh as default-shell

Please ask HPC support if you want to set the zsh as your default login shell.