Question 46405 in Debian Question posted in
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Escape sequences 33[01;36m] vs. 33[1;36m] in PS1 in .bashrc: why the zero? – Debian

I’ve just compared the $PS1 prompts in .bashrc on two of my Debian machines:

PS1='${debian_chroot:+($debian_chroot)}[33[01;36m]u[33[0;90m]@[33[0;32m]h[33[0;90m]:[33[01;34m]w[33[0;90m]$[33[0m] '

PS1='${debian_chroot:+($debian_chroot)}[33[1;36m]u[33[0;37m]@[33[0;32m]h[33[0;37m]:[33[01;34m]w[33[0;37m]$[33[0m] '

As you see, the first sequence says 33[01;, whereas the second has 33[1; on the same position. Do both mean the same (I guess, bold) or do they mean something different? Any idea why the zero has appeared or disappeared? I have no recollection of having introduced/removed this zero myself. A Web search returns numerous occurrences both with and without zero.

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2

Answers


  1. 0

    the ESC[#;#m escape is for the console font color. I’ve seen many subtle variations on escape implementations, so I’m not surprised. Regardless I think both should be interpreted the same way

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  2. 0

    "ANSI" numeric parameters are all decimal integers (see ECMA-48, section 5.4.1 Parameter Representation). In section 5.4.2, it explains

    A parameter string consists of one or more parameter sub-strings, each of which represents a number
    in decimal notation.

    A leading zero makes no difference. Someone noticed the unnecessary character and trimmed it.

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