Replace all dots in filenames except the extension on Linux
for f in .; do pre="${f%.}"; suf="${f##.}"; mv -i -f -- "$f" "${pre//./_}.${suf}"; done
Bash
Count number of directories in the current directory using Linux cli
ls -1 | wc -l
Count number of files in a directory using Linux cli
ls -l . | egrep -c '^-'
One liner: To get available virtual memory
vmstat -s -SM | grep "free memory" | awk -F" " '{print$1}'
[HowTo] Replace ip address using sed
Following one-liner will search for a ip address pattern in the specified file and replace it with the one provided : sed 's/[0-9]\{1,3\}.[0-9]\{1,3\}.[0-9]\{1,3\}.[0-9]\{1,3\}/**IPADDRESS-COMES-HERE**/g' /SourceFilename > /DestinationFilename
How To Get The Current Epoch Time (Unix Timestamp)
PHP PostgreSQL powershell Python ruby shell sql server unix Unix Timestamp vbscript Perl: time PHP: time() Ruby: Time.now # (or Time.new). To display the epoch: Time.now.to_i Python: import time # first, then int(time.time()) Java: long epoch = System.currentTimeMillis()/1000; Microsoft .NET C#: epoch = (DateTime.Now.ToUniversalTime().Ticks - 621355968000000000) / 10000000; VBScript/ASP: DateDiff("s", "01/01/1970 00:00:00", Now()) Erlang: calendar:datetime_to_gregorian_seconds(calendar:now_to_universal_time( now()))-719528*24*3600. # OR element(1, now()) * 10000 + element(2, now()). MySQL: SELECT unix_timestamp(now()) PostgreSQL: SELECT extract(epoch FROM now()); Oracle PL/SQL: SELECT (SYSDATE - TO_DATE('01-01-1970 00:00:00', 'DD-MM-YYYY HH24:MI:SS')) * 24 * 60 * 60 FROM DUAL SQL Server: SELECT DATEDIFF(s, '1970-01-01 00:00:00', GETUTCDATE()) JavaScript: Math.round(new Date().getTime()/1000.0) // getTime() returns time in milliseconds. Unix/Linux Shell: date +%s PowerShell: Get-Date -UFormat "%s" # Produces: 1279152364.63599 Actionscript: (new Date()).time Other OS’s Command line: perl -e "print time" # (If Perl is installed on your system) ColdFusion (CFML) MX 6.1+: #int( getTickCount() / 1000 )# Bash Command Line: date +%s