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A Bash Script to Generate Markdown Tables

Popularity：199 ℃/2024-08-22 10:03:19

Hello everyone, I'm Salty.

Today I'm sharing a very useful bash script toConvert files with separators (e.g. CSV, TSV files) to Markdown tables by manually supplying the cell contents and number of columns or...

The source code is at the end of the article oh! Original link:/2022/pure-bash-markdown-table-generator/

Specific features:

  • Manual Table Generation: Allows users to enter table content and number of columns to generate a standard Markdown-formatted table.
  • File Conversion: CSV or TSV files can be converted to Markdown tables.
  • Option support: Support options such as specifying the number of columns, setting the delimiter, parsing CSV/TSV files, and so on.

Main option:

  • -COLUMNS: Sets the number of columns in the generated table.
  • -sSEPARATOR: Customize the column separator of the input file.
  • --csv cap (a poem)--tsv: Used to parse CSV and TSV files respectively.

A few months ago, I wanted a portable Markdown table generator, so I wrote this onemarkdown-table Script.

At first I just wanted to pass in a bunch of parameters and columns and have it generate the appropriate Markdown table. Like the example below:

markdown-table -4 \
 "Heading 1"  "Heading 2" "Heading 3" "Heading 4" \
 "Hi"         "There"     "From"      "Markdown\!" \
 "Everything" "Is"        "So"        "Nicely Aligned\!"

Once I implemented this, I realized that I could also add support for parsing files with custom separators, such as CSV or TSV.

markdown-table --tsv <

Both methods generate a Markdown table:

| Heading 1  | Heading 2 | Heading 3 | Heading 4      |
| ---------- | --------- | --------- | -------------- |
| Hi         | There     | From      | Markdown       |
| Everything | Is        | So        | Nicely Aligned |

#!/usr/bin/env bash
# Usage: markdown-table -COLUMNS [CELLS]
#        markdown-table -sSEPARATOR < file
#
# NAME
#   markdown-table -- generate markdown tables
#
# SYNOPSIS
#   markdown-table -COLUMNS [CELLS]
#   markdown-table -sSEPARATOR < file
#
# DESCRIPTION
#   markdown-table helps generate markdown tables. Manually supply arguments
#   and a column count to generate a table, or pass in a delimited file to
#   convert to a table.
#
# OPTIONS
#   -COLUMNS
#       Number of columns to include in output.
#
#   -sSEPARATOR
#       String used to separate columns in input files.
#
#   --csv
#       Shortcut for `-s,` to parse CSV files. Note that this is a "dumb" CSV
#       parser -- it won't work if your cells contain commas!
#
#   --tsv
#       Shortcut for `-s$'\t'` to parse TSV files.
#
#   -h, --help
#       Prints help text and exits.
#
# EXAMPLES
#   Build a 4 column markdown table from arguments:
#     markdown-table -4 \
#       "Heading 1"  "Heading 2" "Heading 3" "Heading 4" \
#       "Hi"         "There"     "From"      "Markdown!" \
#       "Everything" "Is"        "So"        "Nicely Aligned!"
#
#   Convert a CSV file into a markdown table:
#     markdown-table -s, < 
#     markdown-table --csv < 
#
#   Convert a TSV file into a markdown table:
#     markdown-table -s$'\t' < 
#     markdown-table --tsv < 

# Call this script with DEBUG=1 to add some debugging output
if [[ "$DEBUG" ]]; then
  export PS4='+ [${BASH_SOURCE##*/}:${LINENO}] '
  set -x
fi

set -e

# Echoes given args to STDERR
#
# $@ - args to pass to echo
warn() {
  echo "$@" >&2
}

# Print the help text for this program
#
# $1 - flag used to ask for help ("-h" or "--help")
print_help() {
  sed -ne '/^#/!q;s/^#$/# /;/^# /s/^# //p' < "$0" |
    awk -v f="$1" '
      f == "-h" && ($1 == "Usage:" || u) {
        u=1
        if ($0 == "") {
          exit
        } else {
          print
        }
      }
      f != "-h"
      '
}

# Returns the highest number in the given arguments
#
# $@ - one or more numeric arguments
max() {
  local max=0 arg

  for arg; do
    (( ${arg:-0} > max )) && max="$arg"
  done

  printf "%s" "$max"
}

# Formats a table in markdown format
#
# $1 - field separator string
format_table() {
  local fs="$1" buffer col current_col=0 current_row=0 min=3
  local -a lengths=()

  buffer="$(cat)"

  # First pass to get column lengths
  while read -r line; do
    current_col=0

    while read -r col; do
      lengths["$current_col"]="$(max "${#col}" "${lengths[$current_col]}")"

      current_col=$((current_col + 1))
    done <<< "${line//$fs/$'\n'}"
  done <<< "$buffer"

  # Second pass writes each row
  while read -r line; do
    current_col=0
    current_row=$((current_row + 1))

    while read -r col; do
      printf "| %-$(max "${lengths[$current_col]}" "$min")s " "$col"

      current_col=$((current_col + 1))
    done <<< "${line//$fs/$'\n'}"

    printf "|\n"

    # If this is the first row, print the header dashes
    if [[ "$current_row" -eq 1 ]]; then
      for (( current_col=0; current_col < ${#lengths[@]}; current_col++ )); do
        printf "| "
        printf "%$(max "${lengths[$current_col]}" "$min")s" | tr " " -
        printf " "
      done

      printf "|\n"
    fi
  done <<< "$buffer"
}

# Main program
main() {
  local arg cols i fs="##$$FS##"

  while [[ $# -gt 0 ]]; do
    case "$1" in
      -h | --help) print_help "$1"; return 0 ;;
      -[0-9]*) cols="${1:1}"; shift ;;
      -s*) fs="${1:2}"; shift ;;
      --csv) fs=","; shift ;;
      --tsv) fs=$'\t'; shift ;;
      --) shift; break ;;
      -*) warn "Invalid option '$1'"; return 1 ;;
      *) break ;;
    esac
  done

  if [[ -z "$fs" ]]; then
    warn "Field separator can't be blank!"
    return 1
  elif [[ $# -gt 0 ]] && ! [[ "$cols" =~ ^[0-9]+$ ]]; then
    warn "Missing or Invalid column count!"
    return 1
  fi

  { if [[ $# -gt 0 ]]; then
      while [[ $# -gt 0 ]]; do
        for (( i=0; i < cols; i++ )); do
          if (( i + 1 == cols )); then
            printf "%s" "$1"
          else
            printf "%s%s" "$1" "$fs"
          fi
          shift
        done

        printf "\n"
      done
    else
      cat
    fi
  } | format_table "$fs"
}

main "$@"
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