Command Line for Creatives

Getting Help

If you ever need help with a <command>, or want to know what it does, here's how to show the information directly in the terminal.

First in PowerShell:

PS C:\> Get-Help <command> -Full

Next in cmd.exe:

C:\> <command> /?

Then again with three examples for bash:

user@user:~$ man <command>
user@user:~$ <command> -h
user@user:~$ <command> --help

Renaming Files Programmatically

Renaming Files With Bash

Rename all files in the current directory ending with .jpg.png to just .png instead:

for file in ./*\.*; do mv "$file" "${file%.jpg.png}.png"; done

%will match the right-most match
%% will match the left-most match
Same for # and ##

More examples replacing a pattern:

# Template, replaces x with y for all files in the current working directory (cwd)
for file in ./*\.*; do if (echo "$file" | grep -Fq "x"); then mv "$file" "$(echo "$file" | sed 's/x/y/g')"; fi; done

# replace .jpg.jpg with .jpg for all files in the current working directory (cwd)
for file in ./*\.*; do if (echo "$file" | grep -Fq ".jpg.jpg"); then mv "$file" "$(echo "$file" | sed 's/.jpg.jpg/.jpg/g')"; fi; done

# replace -- with _ for all files in the current working directory (cwd)
for file in ./*\.*; do if (echo "$file" | grep -Fq "--"); then mv "$file" "$(echo "$file" | sed 's/\-\-/_/g')"; fi; done

The last example required both -- characters be escaped, meaning a \ is in front of each character.

Escaping is required for some symbols and characters that are often used on the command line for special purposes such as modifying the command.

Escaping those characters tells the command line to interpret them literally (as two dashes --) rather than special command modifiers.

If a command ever has unexpected results, (or to avoid unexpected results) try single quoting arguments for a command, or escaping any symbols or characters that aren't plain letters or numbers.

For example:

# single quoting the argument made to the "echo" command
echo 'argument one'

# escaping the space, because spaces are special characters
# how would "echo" know if it's one, or two arguments, without single quotes or escaping?
echo argument\ one

This page from the bash manual provides a good overview of this concept.

Renaming Files With PowerShell

https://docs.microsoft.com/en-us/dotnet/api/system.string.replace?view=net-6.0

https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.management/rename-item?view=powershell-7.2

Rename all files in the current directory ending with .jpg.jpg to end with .jpg:

Get-ChildItem *.jpg.jpg | Rename-Item -NewName { $_.Name -replace '.jpg.jpg','.jpg' }

Finding Files On Your PC

Applies to: Windows, macOS, Linux

Both PowerShell and bash have become cross-platform in recent years, so examples could apply to any OS depending on what you have installed.

Using cmd.exe

dir /S /B C:\Users\User | findstr /R ".\.psw"

The above command finds all .psw files under C:\Users\User.

If you're in a PowerShell prompt you can execute the above command by prepending it with cmd.exe /C:

cmd.exe /C dir /S /B C:\Users\User | findstr /R ".\.psw"

Syntax	Description
`cmd.exe /C`	used to execute Windows command prompt commands, if you're in PowerShell
`dir /S /B C:\Users\User`	`/S` will search recursively, while `/B` displays the filename without additional information
`\|`	the pipeline 'pipes' the output from `command 1` for `command 2` to use
`findstr /R ".\.psw"`	Attempts to find the string (findstr) matching a regular expression of `.\.psw` (Essentially, tell us all of the `.psw` files that you can find)

See the additional syntax of /R regular expressions quick reference with: findstr /?

Using PowerShell

Get-ChildItem -Path C:\Users\User\*.psw -Recurse -Force -ErrorAction SilentlyContinue | Sort-Object -Unique | select -Property FullName

The above command finds all .psw files under C:\Users\User, and shows their file path.

Syntax	Description
`Get-ChildItem -Path C:\Users\User\*.psw -Recurse -Force`	This recursively searches the User's path, for all `.psw` files (when using `-Force`, include hidden directories like `AppData`)
`-ErrorAction SilentlyContinue`	Does not print errors to the terminal if it cannot access a restricted path (which is fine, we would have read access to our Photoshop settings folder)
`Sort-Object -Unique`	All items returned are "objects" in the PowerShell (`.NET`) language. Only show us unique results
`Select -Property FullName`	Give us the full path name to the `.psw` file(s)

It may strengthen your understanding of what's going on by running each part of the command individually to see the output:

PS C:\Users\User> Get-ChildItem -Path C:\Users\User\*.psw -Recurse -Force -ErrorAction SilentlyContinue 
PS C:\Users\User> Get-ChildItem -Path C:\Users\User\*.psw -Recurse -Force -ErrorAction SilentlyContinue | Sort-Object -Unique
PS C:\Users\User> Get-ChildItem -Path C:\Users\User\*.psw -Recurse -Force -ErrorAction SilentlyContinue | Sort-Object -Unique | select -Property FullName

Using bash

find / -type f -name "*.psw" -ls 2>/dev/null

The above command finds all .psw files on the entire hard drive / and shows their file path.

Syntax	Description
`find /`	Executes the `find` binary starting at the base of the filesysytem `/` (on windows you would likely use `/mnt/c/Users/User` for the user directory)
`-type f`	Type = `f`, we're looking for a file
`-name "*.psw"`	Name = `.psw`, we're looking for a name that matches `` (anything) plus `.psw`
`-ls`	List contents of a path, in this case `-ls` will be run on all `*.psw` files we find, which will tell us exactly where they are on the filesystem
`2>/dev/null`	ignore errors (in this case generated by directories we cannot read from)

/dev/null on a Unix filesystem is like the Recycle Bin for the command line, but it's a void. Any output sent there is not shown or recoverable, so send any errors there since we don't need to see directories we don't have access to anyway.

Practical Example

PS C:\Users\User> Get-ChildItem -Path C:\Users\User\*2021*V001*R00[1-7].psd -Recurse -Force -ErrorAction SilentlyContinue | Sort-Object -Unique | select -Property FullName

The above command would return revisions 1 through 7 R00[1-7] of the first version V001 of any .psd file within the C:\Users\User\*2021* path if it exists.

The syntax uses regular expressions to parse strings (letters, numbers, symbols) the basics can be learned and practiced within a day, and will serve you endlessly when dealing with computers. Regular expressions and strings are everywhere, and what you can do with them can become insanely complex.

If you want to learn regular expressions in 4 hours, Joff Thyer's Regular Expressions, Your New Lifestyle course is available on-demand.