Commands tagged grep (409)

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Multiple variable assignments from command output in BASH
It's quite easy to capture the output of a command and assign it in a shell's variable: $ day=$(date +%d) $ month=$(date +%m) But, what if we want to perform the same task with just one program invocation? Here comes the power of eval! date(1) outputs a string like "day=29; month=07; year=11" (notice the semicolons I added on purpose at date's custom output) which is a legal shell line. This like is then parsed and executed by the shell once again with the help of eval. Just setting 3 variables! Inspired by LinuxJournal's column "Dave Taylor's Work the Shell".

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Clear all Windows Event Log entries (cygwin)
Efficiently clear all Windows Event log entries from within a Cygwin terminal. Uses "cygstart" to launch a hidden "PowerShell" session passing a Powershell command to loop through and clear all Windows Event Log entries. Very useful for troubleshooting and debugging. The command should in theory elevate you session if needed. One liner is based on the PowerShell command: $ wevtutil el | foreach { wevtutil cl $_ }

Show linux kernel modules dependencies
Use modprobe to list all the dependencies of a certain kernel module. Handy when debugging system issues.

List all files in current dir and subdirs sorted by size
or $ tree -ifsF --noreport .|sort -n -k2|grep -v '/$' (rows presenting directory names become hidden)

Get a list of ssh servers on the local subnet
Scan the local network for servers who have the ssh port open.

Perl One Liner to Generate a Random IP Address
A bash version.

Convert seconds into minutes and seconds
This is a very simple way to input a large number of seconds and get a more useful value in minutes and seconds. Avoids useless use of echo.

Print a row of characters across the terminal
shorter than alternative

Share your terminal session real-time
One person does `mkfifo foo; script -f foo' and another can supervise real-time what is being done using `cat foo'.


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