Shell – How to correctly extract all command synopses from manpages in /usr/share/man/man1

manshell-script

I'm trying to extract all command synopses from manpages in /usr/share/man/man1 using:

#!/usr/bin/env bash
## synopses - extract all synopses in /usr/share/man/man1

cd /usr/share/man/man1
for i in *.gz; do
    echo "$i:" | sed -E "s/.1.gz|.gz//g"
    man "./$i" | sed -n '/^SYNOPSIS/,/^[A-Z][A-Z][A-Z]/p' | sed -e '1d; $d' | tr -s [:space:]
done

…which provides some measure of success – I get complete output for commands from a to z. But I'm also getting many errors on stderr using both for i in ./*.gz; do man "$i" and for i in *.gz; do man "./$i"as I output to file (synopses > file)1:

<standard input>:27: expected `;' after scale-indicator (got `o')
<standard input>:29: expected `;' after scale-indicator (got `o')
<standard input>:283: name expected (got `\{'): treated as missing
<standard input>:674: warning: macro `as',' not defined (possibly missing space after `as')
<standard input>:174: name expected (got `\{'): treated as missing
<standard input>:161: warning [p 1, 5.5i]: can't break line
<standard input>:594: warning [p 5, 3.8i, div `an-div', 0.0i]: can't break line
<standard input>:569: warning [p 6, 0.0i]: can't break line
<standard input>:147: warning [p 1, 1.8i]: can't break line
<standard input>:205: warning [p 2, 0.2i]: can't break line
<standard input>:525: warning [p 5, 4.5i]: can't break line
<standard input>:157: warning [p 1, 4.8i]: can't break line
<standard input>:351: warning [p 3, 1.8i, div `an-div', 0.0i]: can't break line
<standard input>:147: a space character is not allowed in an escape name
man: can't open man1/zshmisc.1: No such file or directory
man: -:423: warning: failed .so request
man: can't open man1/zshexpn.1: No such file or directory
man: -:423: warning: failed .so request
man: can't open man1/zshparam.1: No such file or directory
man: -:423: warning: failed .so request
man: can't open man1/zshoptions.1: No such file or directory
man: -:423: warning: failed .so request
man: can't open man1/zshbuiltins.1: No such file or directory
man: -:423: warning: failed .so request
man: can't open man1/zshzle.1: No such file or directory
man: -:423: warning: failed .so request
man: can't open man1/zshcompwid.1: No such file or directory
man: -:423: warning: failed .so request
man: can't open man1/zshcompsys.1: No such file or directory
man: -:423: warning: failed .so request
man: can't open man1/zshcompctl.1: No such file or directory
man: -:423: warning: failed .so request
man: can't open man1/zshmodules.1: No such file or directory
man: -:423: warning: failed .so request
man: can't open man1/zshcalsys.1: No such file or directory
man: -:423: warning: failed .so request
man: can't open man1/zshtcpsys.1: No such file or directory
man: -:423: warning: failed .so request
man: can't open man1/zshzftpsys.1: No such file or directory
man: -:423: warning: failed .so request
man: can't open man1/zshcontrib.1: No such file or directory
man: -:423: warning: failed .so request
<standard input>:423: can't open `man1/zshmisc.1': No such file or directory
<standard input>:424: can't open `man1/zshexpn.1': No such file or directory
<standard input>:425: can't open `man1/zshparam.1': No such file or directory
<standard input>:426: can't open `man1/zshoptions.1': No such file or directory
<standard input>:427: can't open `man1/zshbuiltins.1': No such file or directory
<standard input>:428: can't open `man1/zshzle.1': No such file or directory
<standard input>:429: can't open `man1/zshcompwid.1': No such file or directory
<standard input>:430: can't open `man1/zshcompsys.1': No such file or directory
<standard input>:431: can't open `man1/zshcompctl.1': No such file or directory
<standard input>:432: can't open `man1/zshmodules.1': No such file or directory
<standard input>:433: can't open `man1/zshcalsys.1': No such file or directory
<standard input>:434: can't open `man1/zshtcpsys.1': No such file or directory
<standard input>:435: can't open `man1/zshzftpsys.1': No such file or directory
<standard input>:436: can't open `man1/zshcontrib.1': No such file or directory

What are those <standard input> errors about (something escaped?) and why is man ending up not finding some files? How could I make this more robust/efficient?

1. It seems the errors on stderr are the same whatever the implementation/solution I use for the same data. It is striking.

Best Answer

You can't just run man foo.gz It looks like you can run man foo.1.gz but using the -l seems cleaner. From man man:

   -l, --local-file
          Activate `local' mode.  Format and display  local  manual  files
          instead  of  searching  through  the system's manual collection.
          Each manual page argument will be interpreted as an nroff source
          file in the correct format.  No cat file is produced.  If '-' is
          listed as one of the arguments, input will be taken from  stdin.
          When  this  option  is  not used, and man fails to find the page
          required, before displaying the error message,  it  attempts  to
          act as if this option was supplied, using the name as a filename
          and looking for an exact match.

So, your script should be something like:

#!/usr/bin/env bash
## synopses - extract all synopses in /usr/share/man/man1

## No need to cd into the directory, you can just use globs     
for i in /usr/share/man/man1/ajc*.gz; do
    ## This will print the name of the command.      
    basename "${i//.1.gz}"
    man -l "$i"  | 
       awk '/^SYNOPSIS/{a=1; getline}
            (/^[a-zA-z0-9_]/ && a==1){a=0} 
            (a==1 && /./){print}' | tr -s [:space:]

done

The awk command I give works better than your approach (test it on man ajc for example) and now also works on multi-line synopses. Most of the errors you see are irrelevant, others were due to the way you were handling file names. Let me know if this one works better.

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