London | 26-SDC-July | Raihan Sharif | Sprint 4 | implement shell tools python by RaihanSharif · Pull Request #649 · CodeYourFuture/Module-Tools

RaihanSharif · 2026-08-04T23:55:46Z

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Changelist

Implemented cat, ls, wc.

Task code: CYF-1152

all paths that are not accessible as a file/folder throw same error

SlideGauge

Good job, I left several comments, could you fix them please?

SlideGauge · 2026-08-05T21:42:46Z

+    prog="a simple version of wc. Takes in one or more files.",
+    description="ls command line tool which can accept -l -w -c cflags")
+
+parser.add_argument("-l", action="store_true", help="show line count", default="l")


Each flag is declared action="store_true", default="l" (and "w", "c"). With store_true, when the flag is
absent the value falls back to that default string - and a non-empty string is truthy. So run wc -l
sample-files/3.txt: does it print only the line count, or all three? What should default be for a boolean flag so
that "flag not given" reads as false?

...uh, yeah, that's bad.

I've now added a check that if no flags are supplied, then just set them all to true.
Which then means that wc prints the lines, word count, and bytes of the files.

Otherwise, the flags are processed individually, so that any combination of the three will work.

SlideGauge · 2026-08-05T21:44:29Z

+                # {some_str:6} left justifed string, length fo at least 6
+                output.append(f"{line_num:6}\t{line}")
+    elif number_all:
+        for i, line in enumerate(lines, start=1):


format_lines numbers with enumerate(..., start=1) and is called fresh for each file in cat_file. Run cat -n
sample-files/*.txt against the real cat - does the count reset to 1 at each file, or keep climbing? Where would the counter need to live to carry across files?

yes, the numbering starts from 1 for each file in the cat input

cat -n sample-files/* 1 Once upon a time... 1 There was a house made of gingerbread. 1 It looked delicious. 2 I was tempted to take a bite of it. 3 But this seemed like a bad idea... 4 5 There's more to come, though...

python cat:

python3 cat.py -n sample-files/* 1 Once upon a time... 1 There was a house made of gingerbread. 1 It looked delicious. 2 I was tempted to take a bite of it. 3 But this seemed like a bad idea... 4 5 There's more to come, though...

You asked this in the nodeJS version of cat as well. Are you hinting at something, and I'm just not getting it?

Depending on how your system is setup you might not see this.

I think that what the original reviewer is hinting at is, what if you wanted all the numbers for multiple files in sequence? On my machine, it looks like this:

cat -n sample-files/* 1 Once upon a time... 2 There was a house made of gingerbread. 3 It looked delicious. 4 I was tempted to take a bite of it. 5 But this seemed like a bad idea... 6 7 There's more to come, though...

Hi Leon,

I did initially implement cat so that the numbering would be across files. I changed it to reflect the behaviour of my macOS/BSD version of cat which does actually restart numbering for each file it reads from stdin.

This is what it looks like

/bin/cat -n sample-files/1.txt sample-files/2.txt sample-files/3.txt 1 Once upon a time... 1 There was a house made of gingerbread. 1 It looked delicious. 2 I was tempted to take a bite of it. 3 But this seemed like a bad idea... 4 5 There's more to come, though...

I have changed it to do numbering across files. I just pass in a line_num variable (initially set to 1) to the format_lines function, which then increments line_num and returns a list of lines formatted with numbers, and the then the cat_file function increases line_num by the number of lines returned, and calls format_lines on the next file it reads.

This does require a global line_num variable, but it could just easily all be implemented inside of cat_file. It would just change from taking a single path, to taking a list of paths.

SlideGauge · 2026-08-05T21:48:12Z

+            lines = file.readlines()
+
+            if (args.l):
+                if (len(lines) > 0 and lines[-1] == ""):


lines[-1] == "" - but readlines() keeps the trailing \n, so an element is "\n", never "". Does this pop ever
actually run? Check wc -l against real wc on a file that does and doesn't end in a newline.

Thank you for pointing that out, I 'translated' my js code too literally without accounting for how readlines() or how wc actually counts lines.

wc counts the number of '\n' characters, not necessarily non-empty lines. Last empty line is excluded because it doesn't have a '\n' in it.

I've changed my implementation to just read the file, and count the number of '\n' characters. The output now matches the real wc.

It also made my -w logic a bit simpler.

LonMcGregor

Apologies for the delay in continuing this review.

This looks almost complete, I've left a couple of final comments

LonMcGregor · 2026-10-07T11:11:29Z

+            lines = content.split('\n')
+
+            if (args.l):
+                #if (len(lines)) > 0: 


If this code isn't needed anymore, you can remove it entirely instead of commenting. Git will keep a history of old lines if you needed it.

LonMcGregor · 2026-10-07T11:13:04Z

+                # {some_str:6} left justifed string, length fo at least 6
+                output.append(f"{line_num:6}\t{line}")
+    elif number_all:
+        for i, line in enumerate(lines, start=1):


Depending on how your system is setup you might not see this.

I think that what the original reviewer is hinting at is, what if you wanted all the numbers for multiple files in sequence? On my machine, it looks like this:

cat -n sample-files/* 1 Once upon a time... 2 There was a house made of gingerbread. 3 It looked delicious. 4 I was tempted to take a bite of it. 5 But this seemed like a bad idea... 6 7 There's more to come, though...

RaihanSharif added 16 commits August 3, 2026 13:30

set up argparse with -n, -n flags

38c96e9

handle errors when reading file

0591f3f

return exit code 1 for any failed file read

6020eef

seperate out file read and formatting

108fef7

cat function to cat the formatted lines

0c5aeb2

remove stray semicolon

9361dde

set up parser

3617742

read files/folders in a given folder

b28fa81

function to format and print a single directory content

4f62b37

snake case function names

2ad95a6

print multiple files and folders

36c79a6

add very basic error handling

34e629a

all paths that are not accessible as a file/folder throw same error

add a requirements file for argparse import

2d9a740

parser setup

ef611c6

logic completed

575f0bf

wc formatting matches real formatting exactly.

87d8179

RaihanSharif force-pushed the shell-tools-python branch from d5a3942 to 87d8179 Compare August 5, 2026 13:38

add utf-8 encoding to cat

4995bfc

RaihanSharif added the Needs Review Trainee to add when requesting review. PRs without this label will not be reviewed. label Aug 5, 2026

RaihanSharif added 2 commits August 5, 2026 14:47

no need to keep track of file count

0e5e2ee

correctly print error message

1ea4d3e

SlideGauge reviewed Aug 5, 2026

View reviewed changes

SlideGauge added Reviewed Volunteer to add when completing a review with trainee action still to take. and removed Needs Review Trainee to add when requesting review. PRs without this label will not be reviewed. labels Aug 5, 2026

RaihanSharif added Needs Review Trainee to add when requesting review. PRs without this label will not be reviewed. and removed Reviewed Volunteer to add when completing a review with trainee action still to take. labels Aug 5, 2026

implement changes from code review

085a1ac

LonMcGregor reviewed Oct 7, 2026

View reviewed changes

LonMcGregor added Reviewed Volunteer to add when completing a review with trainee action still to take. and removed Needs Review Trainee to add when requesting review. PRs without this label will not be reviewed. labels Oct 7, 2026

RaihanSharif added 2 commits October 9, 2026 12:30

remove dead code

d0e9187

numbering across files

9fa8069

RaihanSharif added Needs Review Trainee to add when requesting review. PRs without this label will not be reviewed. and removed Reviewed Volunteer to add when completing a review with trainee action still to take. labels Oct 9, 2026

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RaihanSharif commented Aug 4, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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RaihanSharif commented Aug 4, 2026 •

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RaihanSharif Aug 5, 2026 •

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