keep-header

Sort a file and keep the first line at the top

$ keep-header [path/to/file] -- sort

$ keep-header [path/to/file] -- [command]

$ cat [path/to/file] | keep-header -- [command]

$ keep-header [path/to/file] -- grep [pattern]

As 'keep-header' is not a standalone command, there is no direct command synopsis for it. Instead, the functionality is achieved through various command-line utilities and scripting techniques, which collectively form the 'keep-header' pattern. The general approach involves separating the header from the data, processing the data, and then rejoining the header with the processed data. For instance, a conceptual representation of how one might preserve a header from a file data.csv while processing it might look like:

header=$(head -n 1 data.csv)
processed_data=$(tail -n +2 data.csv | YOUR_PROCESSING_COMMANDS)
echo -e "$header\n$processed_data"

Alternatively, tools like awk or sed can handle this in a single pass using conditional logic (e.g., NR==1 in awk).

N/A
    Since 'keep-header' is not a specific command, it does not have its own parameters. The options and arguments used are those of the individual Linux commands (like awk, sed, head, tail) that are employed to implement the header preservation pattern. Each of these commands has its own set of parameters to control their specific operations.

The term 'keep-header' refers to a common data processing pattern in Linux and Unix-like environments, rather than a standalone command. It describes the technique of preserving the first line (or a set of initial lines) of a text file, typically a header, while applying transformations or filters to the remaining data lines. This pattern is crucial when working with structured text files like CSV, TSV, or log files, where the header provides essential context (column names) for the data below. Tools like awk, sed, head, and tail are frequently combined to achieve this. The basic idea is to treat the header row(s) differently from the body of the file, either by printing it directly before processing the rest of the file or by skipping it during the main processing step and then prepending it back.

The most important caveat is that 'keep-header' is not a distinct Linux command or utility available in standard distributions. It is a conceptual pattern that must be implemented using existing command-line tools and scripting. Therefore, its exact 'syntax' or 'behavior' is entirely dependent on how a user chooses to combine and configure other commands. There is no man keep-header page. Users must be familiar with text processing tools like awk, sed, head, and tail to effectively apply this pattern.

This example processes a file data.csv (assuming comma-separated values) by printing the header (first line) as is, and then converting all data lines to uppercase.

awk 'NR==1 {print; next} {print toupper($0)}' data.csv

Here, NR==1 checks if it's the first record (line number); if so, it prints the line and skips to the next. Otherwise, it processes the line (converts to uppercase).

This example uses sed to keep the header and substitute 'old' with 'new' in the rest of the lines.

sed '1!s/old/new/g' data.csv

Here, 1! means 'not the first line'. So, the substitution s/old/new/g is applied to all lines except the first.

A common pattern is to split the file, process the data, and then merge back. This example sorts the data part of a file while keeping the header.

(head -n 1 data.csv && tail -n +2 data.csv | sort) > sorted_data.csv

This command first prints the header, then pipes the rest of the file to sort, and the entire output is redirected to sorted_data.csv.

The need to process data files while preserving header information has existed since the early days of computing, particularly with the rise of structured text data formats like CSV and TSV. In the Unix philosophy, tools are designed to do one thing well. Thus, specialized tools like awk and sed evolved to handle complex text manipulations, allowing users to implement patterns like 'keep-header' using their conditional processing capabilities. The concept isn't tied to a specific command's development but rather to the flexible and composable nature of Unix command-line utilities, which allows users to chain commands and apply conditional logic to achieve sophisticated data transformations.

head(1), tail(1), awk(1), sed(1), grep(1), cut(1), paste(1), sort(1)