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PowerShell vs Bash Compared (PowerShell for Unixers)

Xah Lee, 2009-07-26, 2010-08-08

This pages shows the equivalent of PowerShell for common unix commands related to text processing, such as grep, head, find, sort, uniq, wc etc. The version of unix tool used here are Bash and GNU. (that's most linuxes, but not BSDs, Solaris, Mac OS X.)

For simpler things such as “cd”, “mkdir”, “ls”, etc, see PowerShell as Bash.

Quick Mirror

Here is a quick table of constructs that are roughly of the same purpose.

Desc	bash	PowerShell
create new file	touch ff	ni ff -type file
◇	cat ff	cat ff
◇	cat f1 f2 > new.txt	cat f1, f2 > new.txt
Display first n lines	head -n 50 ff	cat ff \| select -first 50
◇	tail	cat file \| select -last 50
◇	split	?
list dirs	find . -type d	Get-ChildItem . -Recurse -name
◇	find . -type f	?
◇	find . -name "*html"	Get-ChildItem . -Recurse -name -include *html
◇	find . -size 0	ls . -recurse \| where {$_.length -eq 0}
◇	find . -type f -size 0 -exec rm {} \;	?
◇	grep xyz f.txt	select-string f.txt -pattern xyz -CaseSensitive
◇	grep xyz *html	select-string *html -pattern xyz -CaseSensitive
◇	grep's --ignore-case or -i	select-string without -CaseSensitive
◇	grep's --invert-match	select-string with -NotMatch
◇	grep's --files-with-matches	◇
◇	cmp	Compare-Object
compare file difference	diff f1 f2	diff (cat f1) (cat f2)
◇	sed	?
print nth column	awk '{print $12 , $7}'	?
◇	sort	sort
◇	uniq	sort -Unique
◇	wc	measure-object
◇	tr	◇
◇	basename	◇
◇	dirname	◇

Work In Progress

Note: this page is a mess. It's work in progress. (started when i wished to convert my log processing bash script to PowerShell)

todo, shew PowerShell equivalent of this:

find . -print0 | xargs -0 -l -i echo "{}";
find . -name "*bmp" -print0 | xargs -0 -l -i basename -s ".bmp" "{}" | xargs -0 -l -i convert "{}.bmp" "{}.png".

Detail

touch

# creating a new file in current dir
touch myfile.txt

# creating a new file in current dir
new-item -name myfile.txt -type "file"

Redirect “>”

# put content in a file
echo "some" > myfile.txt
echo "some more" >> myfile.txt # append

# put content in a file
"some" > myfile.txt
"some more" >> myfile.txt # append

Note that, by default, the PowerShell redirect operator ">" creates files with little endian utf-16 encoding, and lines are hard-wrapped at 80 chars, and line ending uses Windows convension of "\r\n" (ascii 13 and 10).

On unixes, the conventional file encoding is utf-8, and lines are not hard-wrapped (sometimes truncated (deleted) silently), and line ending uses "\n" (ascii 10).

To create unix style output, use out-file, like this:

"1'n2'n3" | out-file -Encoding utf8 -width 999000 myfile.txt

However, the line ending used is still "\r\n". To create unix line ending of just "\n", use:

… | Out-String | %{ $_.Replace("`r`n","`n") } | out-file …

However, the end of the file will still contain a "\r".

cat

Unix “cat” can be used to read a file, or join several files. PowerShell equivalent is “get-content” with alias “cat” too.

# display a file content. (cat is alias of get-content)
cat myfile.txt

Note that by default, PowerShell assumes ascii. You can set your $OutputEncoding like this:

# set $OutputEncoding to utf-8
$OutputEncoding = New-Object -typename System.Text.UTF8Encoding

✻ ✻ ✻

Thanks to Shivashis Saha for addition on “cat”. He also sends the following:

split

For example, if you want to split a line based on ":", you can use the following line:

(given $str is a line with different fields separated by ":")
$temp=@($str -split ":");

Super thanks to Jeffrey Snover of Microsoft for helping on about 10 of the items. (Jeffrey's the inventor of PowerShell)

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