Why my zsh script doesn't echo anything?

Question

script:

#!/bin/zsh
IFS=$'\n' arr=($(alias | grep 'git' | grep "^[g|'g]" | sed 's/=.*//' | sed "s/'//"))
echo $arr

These two lines work in the normal command line:

~/test ·····································································································································  test-Cj2sK_tx
❮ IFS=$'\n' arr=($(alias | grep 'git' | grep "^[g|\'g]" | sed 's/=.*//' | sed "s/'//"))
~/test ·····································································································································  test-Cj2sK_tx
❯ echo $arr
g ga gaa gam gama gamc gams gamscp gap gapa gapt gau gav gb gbD gba gbd gbda gbl gbnm gbr gbs gbsb gbsg gbsr gbss gc gc!' gca gca!' gcam gcan!' gcans!' gcas gcasm gcb gcd gcf gcl gclean gcm gcmsg gcn!' gco gcount gcp gcpa gcpc gcs gcsm gd gdca gdct gdcw gds gdt gdw gf gfa gfg gfo gg gga ggpull ggpush ggsup ghh gignore gignored git-svn-dcommit-push gk gke gl glg glgg glgga glgm glgp glo glod glods glog gloga glol glola glols glp glum gm gma gmom gmt gmtvim gmum gp gpd gpf gpf!' gpoat gpristine gpsup gpu gpv gr gra grb grba grbc grbd grbi grbm grbo grbs grev grh grhh grm grmc grmv groh grrm grs grset grss grst grt gru grup grv gsb gsd gsh gsi gsps gsr gss gst gsta gstaa gstall gstc gstd gstl gstp gsts gsu gsw gswc gtl gts gtv gunignore gunwip gup gupa gupav gupv gwch gwip

However, it doesn't work when these two commands are in the script file...

~/test ·····································································································································  test-Cj2sK_tx
❯ /bin/zsh ./d-alias.sh
# nothing here...

Thank you for any help. Many thanks.

Answer 1

There is a much easier way to do what you want:

print -r -- ${(k)aliases[(R)*git*]}

• $aliases is a special hash table containing all aliases. (See http://zsh.sourceforge.net/Doc/Release/Zsh-Modules.html#The-zsh_002fparameter-Module)
• $...[(R)...] does a reverse lookup: It fetches all key-value tuples where the value (not the key) matches the query. (See http://zsh.sourceforge.net/Doc/Release/Parameters.html#Subscript-Flags)
• ${(k)...} returns only the keys (not the values). (See http://zsh.sourceforge.net/Doc/Release/Expansion.html#Parameter-Expansion-Flags)

---

However, as to your main question: When you do /bin/zsh ./d-alias.sh, it doesn't work, because you are starting a new shell in which to run your script. When you start a new shell from within another shell, the new shell inherits the exported environment variables from the originating shell, but nothing else. Additionally, if you start a new shell to run a script or command (as opposed to simply starting a new shell), it is not considered to be interactive. This means that your .zshrc will not get sourced and thus your aliases won't be initialized.

The solution is to instead load your script as a function:

% mkdir -p ~/Functions
% print 'print -r -- ${(k)aliases[(R)$~1]}' >> ~/Functions/d-alias
% fpath+=( ~/Functions )
% autoload -Uz d-alias
% d-alias '*git*'
g ga gaa gam gama gamc gams gamscp gap gapa gapt gau gav gb gbD gba gbd gbda gbl gbnm gbr gbs gbsb gbsg gbsr gbss gc gc!' gca gca!' gcam gcan!' gcans!' gcas gcasm gcb gcd gcf gcl gclean gcm gcmsg gcn!' gco gcount gcp gcpa gcpc gcs gcsm gd gdca gdct gdcw gds gdt gdw gf gfa gfg gfo gg gga ggpull ggpush ggsup ghh gignore gignored git-svn-dcommit-push gk gke gl glg glgg glgga glgm glgp glo glod glods glog gloga glol glola glols glp glum gm gma gmom gmt gmtvim gmum gp gpd gpf gpf!' gpoat gpristine gpsup gpu gpv gr gra grb grba grbc grbd grbi grbm grbo grbs grev grh grhh grm grmc grmv groh grrm grs grset grss grst grt gru grup grv gsb gsd gsh gsi gsps gsr gss gst gsta gstaa gstall gstc gstd gstl gstp gsts gsu gsw gswc gtl gts gtv gunignore gunwip gup gupa gupav gupv gwch gwip

Answer 2

Where are your aliases being defined?

If you run your script as ./name.zsh, it will run a new copy of zsh rather than a forked copy of your current shell. The new copy of zsh will source your ~/.zshrc, but not your ~/.zprofile or ~/.profile, since it is not a login shell. Edit: As Kusalananda mentions below, it won't source ~/.zshrc for scripts, only ~/.zshenv will be sourced for zsh scripts.

Pipes, loops, $(), and functions are run as forks of the current shell, and retain all of the aliases and functions, so '$(alias)' inherits the current aliases and functions, while 'zsh -c alias' does not. Running a shell script also always created a new process for the script, just like 'zsh -c alias', instead of forking the current shell.

It should work by sourcing it into the current shell:

. ./name.zsh

If your aliases are defined in ~/.zprofile or ~/.profile, then they should be moved to ~/.zshrc. which is sourced for every copy of zsh instead of just a login shell.