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PowerShell, shell: Remove comments from source (Windows/Linux/BSD)

by Kliment Andreev
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norem for Linux/*BSD

A small utility written in Bourne shell (compatible with both sh and bash, which means works without changes on all *BSD/Linux) that strips comments from a source file. E.g. I am too lazy to scroll through /etc/ssh/sshd_config file to look for any valid directives.
Here is /etc/ssh/sshd_config on FreeBSD.

#       $OpenBSD: sshd_config,v 1.98 2016/02/17 05:29:04 djm Exp $
#       $FreeBSD: releng/10.3/crypto/openssh/sshd_config 296853 2016-03-14 13:05:13Z des $

# This is the sshd server system-wide configuration file.  See
# sshd_config(5) for more information.

# This sshd was compiled with PATH=/usr/bin:/bin:/usr/sbin:/sbin

# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented.  Uncommented options override the
# default value.

# Note that some of FreeBSD's defaults differ from OpenBSD's, and
# FreeBSD has a few additional options.

#Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::

# The default requires explicit activation of protocol 1
#Protocol 2

# HostKey for protocol version 1
#HostKey /etc/ssh/ssh_host_key
# HostKeys for protocol version 2
#HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_dsa_key
#HostKey /etc/ssh/ssh_host_ecdsa_key
#HostKey /etc/ssh/ssh_host_ed25519_key

# Lifetime and size of ephemeral version 1 server key
#KeyRegenerationInterval 1h
#ServerKeyBits 1024

# Ciphers and keying
#RekeyLimit default none

# Logging
# obsoletes QuietMode and FascistLogging
#SyslogFacility AUTH
#LogLevel INFO

# Authentication:

#LoginGraceTime 2m
#PermitRootLogin no
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10

#RSAAuthentication yes
#PubkeyAuthentication yes

# The default is to check both .ssh/authorized_keys and .ssh/authorized_keys2
#AuthorizedKeysFile .ssh/authorized_keys .ssh/authorized_keys2

#AuthorizedPrincipalsFile none

#AuthorizedKeysCommand none
#AuthorizedKeysCommandUser nobody

# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
#RhostsRSAAuthentication no
# similar for protocol version 2
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# RhostsRSAAuthentication and HostbasedAuthentication
#IgnoreUserKnownHosts no
# Don't read the user's ~/.rhosts and ~/.shosts files
#IgnoreRhosts yes

# Change to yes to enable built-in password authentication.
#PasswordAuthentication no
#PermitEmptyPasswords no

# Change to no to disable PAM authentication
#ChallengeResponseAuthentication yes

# Kerberos options
#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
#KerberosGetAFSToken no

# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes

# Set this to 'no' to disable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the ChallengeResponseAuthentication and
# PasswordAuthentication.  Depending on your PAM configuration,
# PAM authentication via ChallengeResponseAuthentication may bypass
# the setting of "PermitRootLogin without-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and ChallengeResponseAuthentication to 'no'.
#UsePAM yes

#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
#X11Forwarding yes
#X11DisplayOffset 10
#X11UseLocalhost yes
#PermitTTY yes
#PrintMotd yes
#PrintLastLog yes
#TCPKeepAlive yes
#UseLogin no
#UsePrivilegeSeparation sandbox
#PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
#UseDNS yes
#PidFile /var/run/sshd.pid
#MaxStartups 10:30:100
#PermitTunnel no
#ChrootDirectory none
#VersionAddendum FreeBSD-20160310

# no default banner path
#Banner none

# override default of no subsystems
Subsystem       sftp    /usr/libexec/sftp-server

# Example of overriding settings on a per-user basis
#Match User anoncvs
#       X11Forwarding no
#       AllowTcpForwarding no
#       PermitTTY no
#       ForceCommand cvs server

With this utility, I can just do:

norem -f /etc/ssh/sshd_config

… and voila…You have the meat without the bones.

Subsystem       sftp    /usr/libexec/sftp-server

Almost all *nix utilities have “#” as a comment, but some languages such as Java and C++ use “//” for comments. In this case, we have to run:

norem -f file -c "/"

The utility is not smart enough for multi-line comments such as “/*…*/”
Here is the source:

#!/bin/sh

usage()
{
    echo "usage: norem [-f file ] | [-c char] | [-e]] | [-h]]"
    echo "Prints a file skipping the lines that start with -c"
    echo "By default empty lines are not printed, use -e yes to include them"
    echo "Kliment Andreev - 2016"
}

if [ "$#" == "0" ]; then
        usage
        exit 1
fi

while [ $# -gt 0 ]; do
        key="$1"

        case $key in
                -f|--file)
                        FILENAME="$2"
                    shift
                        ;;
        -c|--char)
                        CHARACTER="$2"
                        shift
                ;;
                -e|--empty)
                EMPTY="$2"
                shift
                ;;
        *)
                usage
                        exit
                ;;
        esac
        shift
done

if [ -z "${CHARACTER}" ]; then
        CHARACTER="#"
fi

if [ -z "${EMPTY}" ]; then
        cat ${FILENAME} | sed "/^\\${CHARACTER}/d" | awk /./
else
        cat ${FILENAME} |sed "/^\\${CHARACTER}/d"
fi

norem for PowerShell

The same utility for PowerShell. The input parameters are the same.

Param(
	[string]$fileName,
	[string]$char="#",
	[string]$empty
)

function usage {
    Write-Host "usage: norem [-f file ] | [-c char] | [-e]]"
    Write-Host "Prints a file skipping the lines that start with -c"
    Write-Host "By default empty lines are not printed, use -e yes to include them"
    Write-Host "Kliment Andreev - 2016"
}

if ($psboundparameters.Count -eq 0) {
    usage
    exit
}

if ($empty.ToUpper().Contains("Y")) {
    Get-Content $fileName | Where { $_ -notmatch "^" + $char }
}
else {
    Get-Content $fileName | Where { $_ -notmatch "^" + $char } | Where {$_.trim() -ne ""}
}
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