colrm

Remove first column of stdin

$ colrm [1 1]

$ colrm [3]

$ colrm [3 5]

colrm [startcol [endcol]]

startcol
    Positive integer (1-based) for first column to remove.

endcol
    Optional positive integer for last column to remove; defaults to line end.

colrm is a Unix utility that removes designated columns from lines of text read from standard input, outputting the modified lines to standard output. Columns are numbered starting from 1 at the left edge. It accepts one or two positive integer arguments: the starting column number, and optionally the ending column number.

If only startcol is given, it deletes all characters from that column to the end of each line. With both startcol and endcol, it removes characters from startcol through endcol inclusive.

Column positions account for tabs, which are treated as advancing to the next tab stop every 8 columns (equivalent to expanding tabs into spaces). Backspace characters move the position left by 8 columns. This fixed-width assumption suits legacy fixed-format data like old reports or printer output.

colrm excels at position-based trimming, contrasting with delimiter-based tools like cut. It's stdin-only, so process files via pipes: cat data.txt | colrm 20. Useful for anonymizing fixed-position fields or formatting tables.

Expectations include integer-only args (no validation if endcol < startcol; it removes nothing extra). No file arguments or options in standard implementations.

Stdin-only; pipe files to use.
Fixed 8-column tabstops; no custom width.
Poor multibyte/UTF-8 support (counts bytes).
No error if endcol < startcol (removes startcol to endcol anyway).
Args must be integers; non-numeric input ignored.

Tabs count as 1-8 spaces to next multiple of 8 column. E.g., tab in column 1 advances to column 9.

echo '1234567890' | colrm 5 → '1234'
echo '1234567890' | colrm 4 7 → '123890'
seq 1 3 | colrm 3 → '1
2
3'

Originated in Programmer's Workbench (PWB) Unix 1.0 around 1977; standardized in POSIX.1-2008. Included in BSD (4.3BSD+), Linux via bsdmainutils package.

cut(1), col(1), expand(1), column(1)