chars

Determine the end-of-line format, tabs, bom, and nul characters

Usage

• For help, run chars -h

chars v2.4.0
Determine the end-of-line format, tabs, bom, and nul
https://github.com/jftuga/chars

Usage:
chars [filename or file-glob 1] [filename or file-glob 2] ...
  -F	when used with -f, only display a list of failed files, one per line
  -b	examine binary files
  -c	add comma thousands separator to numeric values
  -e string
        exclude based on regular expression; use .* instead of *
  -f string
        fail with OS exit code=100 if any of the included characters exist; ex: -f crlf,nul,bom8
  -j	output results in JSON format; can't be used with -l; does not honor -t or -c
  -l int
        shorten files names to a maximum of this length
        shorten files names to a maximum of this length
  -t	append a row which includes a total for each column
  -v	display version and then exit

Notes:
Use - to read a file from STDIN
On Windows, try: chars *  -or-  chars */*  -or-  chars */*/*

Installation

• macOS: brew update; brew install jftuga/tap/chars
• Binaries for Linux, macOS and Windows are provided in the releases section.

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Example 1

• Run chars with no additional cmd-line switches
• • Only report files in the current directory
• • Report text files only since -b is not used

PS C:\chars> .\chars.exe *
+-----------------+------+-----+-----+------+------+-------+-----------+
|    FILENAME     | CRLF | LF  | TAB | NUL  | BOM8 | BOM16 | BYTESREAD |
+-----------------+------+-----+-----+------+------+-------+-----------+
| .goreleaser.yml |    0 |  59 |   0 |    0 |    0 |     0 |      1066 |
| LICENSE         |    0 |  21 |   0 |    0 |    0 |     0 |      1068 |
| README.md       |    0 |  92 |   0 |    0 |    0 |     0 |      3510 |
| chars.go        |    0 | 246 | 328 |    0 |    0 |     0 |      6477 |
| go.mod          |    0 |  10 |   2 |    0 |    0 |     0 |       188 |
| go.sum          |    0 |   6 |   0 |    0 |    0 |     0 |       533 |
| testfile1       |    0 |  22 |   0 | 3223 |    0 |     1 |      6448 |
+-----------------+------+-----+-----+------+------+-------+-----------+

Example 2

• Run chars with -e and -l cmd-line switches
• • Only report files starting with p in the C:\Windows\System32 directory
• • Exclude all files matching perf.*dat
• • Shorten filenames to a maximum length of 32

PS C:\chars> .\chars.exe -e perf.*dat -l 32 C:\Windows\System32\p*
+----------------------------------+------+----+-----+------+------+-------+-----------+
|             FILENAME             | CRLF | LF | TAB | NUL  | BOM8 | BOM16 | BYTESREAD |
+----------------------------------+------+----+-----+------+------+-------+-----------+
| C:\Windows\System32\pcl.sep      |   11 |  0 |   0 |    0 |    0 |     0 |       150 |
| C:\Windows\System32\perfmon.msc  | 1933 |  0 |   0 |    0 |    0 |     0 |    145519 |
| C:\Windows\Sys...tmanagement.msc | 1945 |  0 |   0 |    0 |    0 |     0 |    146389 |
| C:\Windows\System32\pscript.sep  |    2 |  0 |   0 |    0 |    0 |     0 |        51 |
| C:\Windows\Sys...eryprovider.mof |    0 | 61 |   0 | 2073 |    0 |     1 |      4148 |
+----------------------------------+------+----+-----+------+------+-------+-----------+

Example 3

• Pipe STDIN to chars
• Use JSON output, with -j

$ curl -s https://example.com/ | chars -j

[
    {
        "filename": "STDIN",
        "crlf": 0,
        "lf": 46,
        "tab": 0,
        "bom8": 0,
        "bom16": 0,
        "nul": 0,
        "bytesRead": 1256
    }
]

Example 4

• Fail when certain characters are detected, with -f
• • OS exit code on a -f failure is always 100
• • -f is a comma-delimited list containing: crlf, lf, tab, nul, bom8, bom16

$ chars -f lf,tab /etc/group ; echo $?
+------------+------+----+-----+-----+------+-------+-----------+
|  FILENAME  | CRLF | LF | TAB | NUL | BOM8 | BOM16 | BYTESREAD |
+------------+------+----+-----+-----+------+-------+-----------+
| /etc/group |    0 | 58 |   0 |   0 |    0 |     0 |       795 |
+------------+------+----+-----+-----+------+-------+-----------+

100

Example 5

• Fail when certain characters are detected, with -f
• Only output failed file names, with -F

$ chars -f lf,tab -F /etc/gr* ; echo $?
/etc/group
/etc/group.bak

100

Example 6

• Output to JSON, with -j
• Use -e to exclude and filenames starting with go, such as go.mod and go.sum
• Use jq to output to CSV containing two columns: filename, tab
• • Only include files that contain tab characters

$ chars -e '^go' -j * | jq -r '.[] | select(.tab > 0) | [.filename,.tab] | @csv'
"case.go",80
"chars.go",475

Example 7

• Output totals, with -t
• Output commas in numeric values, with -c
• Exclude files containing .g*, with -e

PS C:\chars> .\chars.exe -t -c -e "\.g.*" *
+-----------------+------+-----+-----+-----+------+-------+-----------+
|    FILENAME     | CRLF | LF  | TAB | NUL | BOM8 | BOM16 | BYTESREAD |
+-----------------+------+-----+-----+-----+------+-------+-----------+
| LICENSE         |    0 |  21 |   0 |   0 |    0 |     0 |     1,068 |
| README.md       |    0 | 178 |   4 |   0 |    0 |     0 |     6,656 |
| STATUS.md       |    0 |  50 |   0 |   0 |    0 |     0 |     3,055 |
| go.mod          |    0 |  11 |   3 |   0 |    0 |     0 |       214 |
| go.sum          |    0 |   9 |   0 |   0 |    0 |     0 |       795 |
| TOTALS: 5 files |    0 | 269 |   7 |   0 |    0 |     0 |    11,788 |
+-----------------+------+-----+-----+-----+------+-------+-----------+

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Reading from STDIN on Windows

• YMMV when piping to STDIN under Windows
• • Under cmd, instead of type input.txt | chars, use < redirection when possible: chars < input.txt
• • Under a recent version of powershell, use Get-Content -AsByteStream input.txt | chars instead of just Get-Content input.txt | chars
• cmd and powershell will skip BOM characters; these 2 fields will both report a value of 0
• cmd and powershell will skip NUL characters; this field report a value of 0
• cmd will convert LF to CRLF for UTF-16 encoded files
• powershell will convert LF to CRLF
• Piping from programs such as curl will return LF characters under cmd, but CRLF under powershell
• • Under powershell, consider using curl --output

Case Folding on Windows

• Case folding on Windows is somewhat implemented in case.go.
• • This programs attempts case-insensitive filename matching since this is the expected behavior on Windows.
• • It is hard-coded to English.

Wikipedia

• Newline - CRLF vs LF
• Tab key
• Null character
• Byte order mark - BOM-8 vs BOM-16

Acknowledgments

• ellipsis - Go module to insert an ellipsis into the middle of a long string to shorten it
• tablewriter - ASCII table in golang
• /u/skeeto and /u/petreus provided code review and suggestions