Linux – How to see if a file has CAP_NET_ADMIN

capabilitiesfileslinux

I ran the following command:

sudo setcap cap_net_raw,cap_net_admin,cap_net_bind_service+eip `which nmap`

Now I'd like to add to my ~/.zshrc a line that detects such settings and exports NMAP_PRIVILEGED=1. How could I do that?

Best Answer

Just use getcap:

if nmap --version >/dev/null && getcap `which nmap` | grep -q cap_net_raw; then
  export NMAP_PRIVILEGED="1"
else
  echo "WARNING: No Nmap with cap_net_raw in \$PATH!" >&2
fi

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Gzip – How to Keep Original File

For GNU gzip 1.6 or above, FreeBSD and derivatives or recent versions of NetBSD, see don_cristi's answer.

With any version, you can use shell redirections as in:

gzip < file > file.gz

When not given any argument, gzip reads its standard input, compresses it and writes the compressed version to its standard output. As a bonus, when using shell redirections, you don't have to worry about files called "--help" or "-" (that latter one still being a problem for gzip -c --).

Another benefit over gzip -c file > file.gz is that if file can't be opened, the command will fail without creating an empty file.gz (or overwriting an existing file.gz) and without running gzip at all.

A significant difference compared to gzip -k though is that there will be no attempt at copying the file's metadata (ownership, permissions, modification time, name of uncompressed file) to file.gz.

Also if file.gz already existed, it will silently override it unless you have turned the noclobber option on in your shell (with set -o noclobber for instance in POSIX shells).

Gzip Files – How to Gunzip Files Recursively

You can use

gunzip -r Personal

which works the same as

gzip -d -r Personal

If gzip on your system does not have the -r option (e.g. busybox's gzip) , you can use

find Personal -name "*.gz" -type f -print0 | xargs -0 gunzip

Best Answer

Related Solutions

Gzip – How to Keep Original File

Gzip Files – How to Gunzip Files Recursively

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