+++
title = "Check If a Command/Executable Exists from Shell Script"
author = ["Kaushal Modi"]
description = """
  Shell script snippets to check if you have an executable or binary
  installed in `PATH`.
  """
date = 2016-11-23T17:07:26-05:00
tags = ["bash", "tcsh", "executable", "exists", "binary"]
categories = ["unix", "shell"]
draft = false
creator = "Emacs 28.1.50 (Org mode 9.5.4 + ox-hugo)"
+++

<div class="ox-hugo-toc toc">

<div class="heading">Table of Contents</div>

- [Bash Shell](#bash-shell)
- [Tcsh Shell](#tcsh-shell)

</div>
<!--endtoc-->

I often need to check if a particular executable is present in the
`PATH` before I can proceed with what I am doing in a shell
script. Also, I need to work with both `tcsh` and `bash`
scripts. Below presents the solution that has worked for these shell
scripts for me.


## Bash Shell {#bash-shell}

The below solution using `hash` was with the help of [this SO solution](https://stackoverflow.com/a/677212/1219634).

```sh
if ! hash some_exec 2>/dev/null
then
    echo "'some_exec' was not found in PATH"
fi
```

Here is the _tl;dr_ from the above SO solution:

> Where bash is your shell/hashbang, consistently use `hash` (for
> commands) or `type` (to consider built-ins &amp; keywords). When writing a
> POSIX script, use `command -v`.


## Tcsh Shell {#tcsh-shell}

As it turns out, the `tcsh` shell does not have the same `hash`
command as the `bash` shell.

But the below solution using `where` which I found with the help of
[this SO solution](https://stackoverflow.com/a/22058620/1219634) works fine.

```tcsh
if ( `where some_exec` == "" ) then
    echo "'some_exec' was not found in PATH"
endif
```

[//]: # "Exported with love from a post written in Org mode"
[//]: # "- https://github.com/kaushalmodi/ox-hugo"