display typedefs, structs, unions and functions provided by a header file

cpp /usr/include/stdio.h | grep -v '^#' | grep -v '^$' | less
will display typedefs, structs, unions and functions declared in 'stdio.h'(checkout _IO_FILE structure). It will be helpful if we want to know what a particular header file will offer to us. Command 'cpp' is GNU's C Preprocessor.

These Might Interest You

  • Also removes translator comments. You can remove the header by omitting --keep-header, but if your msgids contain non-ASCII characters you will need the header to specify a suitable charset.


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    msgfilter --keep-header --input input.po awk '{}' | sed '/^#$/d; /^#[^\:\~,\.]/d' >empty.po
    seanf · 2013-02-08 08:05:32 0
  • You can display, save and restore the value of $IFS using conventional Bash commands, but these functions, which you can add to your ~/.bashrc file make it really easy. To display $IFS use the function ifs shown above. In the sample output, you can see that it displays the characters and their hexadecimal equivalent. This function saves it in a variable called $saveIFS: sifs () { saveIFS=$IFS; } Use this function to restore it rifs () { IFS=$saveIFS; } Add this line in your ~/.bashrc file to save a readonly copy of $IFS: declare -r roIFS=$IFS Use this function to restore that one to $IFS rrifs () { IFS=$roIFS; } Show Sample Output


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    ifs () { echo -n "${IFS}"|hexdump -e '"" 10/1 "'\''%_c'\''\t" "\n"' -e '"" 10/1 "0x%02x\t" "\n\n"'|sed "s/''\|\t0x[^0-9]//g; $,/^$/d"
    dennisw · 2009-10-10 22:41:35 0
  • This command finds all of the functions defined in any shell script you specify including .bashrc


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    functions(){ read -p "File name> "; sort -d $REPLY | grep "(){" | sed -e 's/(){//g' | less; }
    LinuxMan · 2010-12-01 18:49:48 0
  • Show disk space info, grepping out the uninteresting ones beginning with ^none while we're at it. The main point of this submission is the way it maintains the header row with the command grouping, by removing it from the pipeline before it gets fed into the sort command. (I'm surprised sort doesn't have an option to skip a header row, actually..) It took me a while to work out how to do this, I thought of it as I was drifting off to sleep last night! Show Sample Output


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    df -h | grep -v ^none | ( read header ; echo "$header" ; sort -rn -k 5)
    purpleturtle · 2011-03-16 14:25:45 1

What Others Think

cpp /usr/include/stdio.h | awk '!/^#/ && !/^$/' | less
sputnick · 472 weeks and 1 day ago
Great!! I learnt how we can simplify awk, normally I'm using, awk '$0 !~ /^#/ && $0 !~ /&$/ {print $0;}' to achieve what you did.
mohan43u · 472 weeks ago

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Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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