Difference between revisions of "User:Ted"

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m (→‎↑ ↓ Expect Utility by Don Libes)
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*  https://stackoverflow.com/questions/15965504/how-to-create-log-file-for-tcl-script
 
*  https://stackoverflow.com/questions/15965504/how-to-create-log-file-for-tcl-script
  
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From the manual page for expect ___:
  
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<ul>
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<i>
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<pre>
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      log_file [args] [[-a] file]
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            If a filename is provided, log_file will record a transcript of the session (beginning at that point) in
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            the file.  log_file will stop recording if no argument is given.  Any previous log file is closed.
  
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            Instead  of  a  filename,  a Tcl file identifier may be provided by using the -open or -leaveopen flags.
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            This is similar to the spawn command.  (See spawn for more info.)
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            The -a flag forces output to be logged that was suppressed by the log_user command.
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            By default, the log_file command appends to old files rather than truncating them, for  the  convenience
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            of  being  able  to  turn  logging off and on multiple times in one session.  To truncate files, use the
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            -noappend flag.
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            The -info flag causes log_file to return a description of the most recent non-info arguments given.
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</pre>
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</i>
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<ul>
  
 
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Revision as of 16:15, 30 January 2018

-- 2017-07-21 शुक्रवार --
User Ted's wiki page at Neela Nurseries


OVERVIEW

This wiki document a starting point of Ted's notes on Linux use and configuration, Open Source Software and web development. Recent summer 2017 efforts of Ted's are focused on several high-level programming language and web development frameworks, which can be studied and used separately but are often glued together to achieve meaningful tasks and end-user tools and interfaces. This personal page of Ted's notes on Neela Nurseries wiki not yet well organized, but here as a quick stash point for holding useful references, and a starting point for more complete and formal documentation.



- 2017-10-05 - Ted noting here that would be good to have a technical glossary to make easily accessible all the technical terms which arise in daily work and exploration of technologies . . .


- 2017-10-19 - TO-DO list: 

  *  [✓] complete LFS 8.1 exercise
  *  [ ] configure xserver to run stand-along without window manager (seems to be working on 1604 spare LTS host . . .)
  *  [ ] set up two mysql servers on one host
  *  [ ] write "best photo contribution" practices page for ASI
  *  [ ] code "re-use or reference text block" module for MediaWiki  <-- this needs further explanation - TMH 
  *  [ ] in local Neela Nurseries PHP code base, amend hybrid building of nav menus to include highlighting parent page of given viewed page
  *  [ ] in OpenCart 2.x find way to customize top-of-page information and links
  *  [ ] in OpenCart 2.x find way to format product lists as compact lists, like Gmail inbox or Windows 'list view' of files



↑ ↓ Mediawiki Issues and Notes

- 2018-01-22 - While editing sidebar of Mediawiki instance at Neela, Ted noticing a difference in Mediawiki's treatment of hyperlinks in the sidebar. Links to external sites don't appear, and links to internal pages require single square brace enclosure to appear with alternate text as a link label . . . 

<!--
** [https://buildroot.org/downloads/manual/manual.html Buildroot manual]
<a href="https://buildroot.org/downloads/manual/manual.html">Buildroot manual</a>

- 2018-01-22 MON -
** https://wiki.neelanurseries.com/index.php/Nn_embedded_linux_notes#.E2.86.91_.E2.86.93_Buildroot|Buildroot notes . . . only 'notes' shows as non-link text - TMH
-->



↑ ↓ Web Site Building Blocks - Summer 2017 Work

Web site building blocks now a separate wiki document, as of 2018-01-08. - TMH



↑ ↓ Linux Packages (Separate Article)

Linux software package notes a separate wiki document on Neela wiki. - TMH



- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

↑ ↓ Bash Shell Scripting

Shell scripting and use of built-in shell commands is a practical knowledge to employ, when working in Unix-like environments. One common task is to find all the instances of a given file or program. The locate command can perform this kind of search, but it's results don't show whether the file instances differ. To check at the rough level of file size, we can use a one-line shell script technique involving shell piping, to "long list" the results of the locate command, like this . . . 

  $ for file in `locate tavrasm | grep 'asm$'`; do ls -l ${file}; done

Hmm strange, the above command calls `grep` with a pattern that ends in the shell end-of-line anchoring character $, and appears to filter for results of `locate` which end in 'asm'. But on 2017-09-12 needed to add a "one or more wildcard" character pattern to limit search results for instances of `locate` results ending in 'qemu': 

$ locate qemu | grep '.*qemu$'

Why the apparent difference in command invocation? Need to test . . . - TMH


Command to break out first ten $PATH environment variable to individual paths each shown on a line of the shell: 

for path in `echo $PATH | cut -d':' -f1-10 --output-delimiter=' '`; do echo $path; done


↑ ↓ edit point - shell variable quoting

- 2017-10-19 THU -

Running into issues when need to expand shell variable in single quotes pair . . .

Stack Exchange, Unix forum post 178411
TLPD Advanced Bash Scripting Guide, chapter 4.2 example 4-3 double quotes preserve white space


WIKI WISH LIST - While adding to wiki, Ted noting that would be useful to have relative-depth wiki section markers. The standard wiki section markers '== ==', '=== ===' and similar have fixed depth. That is, '== ==' is always a top-level or first-level section in a wiki document, '=== ===' is always a sub-subsection of wiki documents, and '==== ====' a sub-sub-section. When section gets re-factored into its own article, would be handy to have those section markers rise up to levels of top-most and successive section markers. - TMH



↑ ↓ example shell script - back up several databases

 
Here is a simple shell script to call mysqldump utility and back up several databases. Couple of things Ted wants to add to this script include script variables to hold back-up filename prefix and infix patterns, and an option to compress the MYSQL dump files . . .

Figure x - shell script to back-up multiple MYSQL databases 


#!/bin/bash


DATABASE_LIST="information_schema mysql drupal_8p0 phpmyadmin wiki_database"

user="root"
pass_phrase_for_mysql="mysql_user_password"
options_extra="--skip-lock-tables"

response="n"

mode_interactive="n"



echo "shell script starting,"



for database in ${DATABASE_LIST};
do echo "backing up alta-ubuntu database $database . . .";

#    command="mysqldump --databases $database -u$user -p$pass_phrase_for_mysql $options_extra >> au-database-back-up--${database}.sql"
    command="mysqldump --databases $database -u$user -p$pass_phrase_for_mysql $options_extra"
    redirect="au-database-back-up--${database}.sql"

    if [ $mode_interactive = 'y' ]; then

        echo "build command '$command' and database back-up filename'$redirect',"
        echo "full command will be '$command' > '$redirect',"
        echo "trying running this command and redirect? [y/N/q]  yes, no, 'q' to quit"

        read response
        if [ $response = 'Y' -o $response = 'y' ]; then
            ${command} > $redirect
        elif [ $response = 'N' -o $response = 'n' ]; then
            echo "skipping present command . . ."
        elif [ $response = 'Q' -o $response = 'q' ]; then
            echo "stopping script '$0' and exiting."
            break
        fi
        echo

    else

        echo "$0:  backing up database '$database' to file '$redirect' . . ."
        ${command} > $redirect
        ls -l $redirect

    fi

done


echo "done."

exit 0

↑ ↓ show kernel version script

Following script 'showkversion' can be used in a Linux kernel source tree to determine the kernel's version number, based on the number elements defined in the kernel's top level makefile.

Figure x - simple bash script to show kernel version in root of kernel sources tree 

#!/bin/bash

## - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
## Started 2017-12-15 FRI - script to parse and show Linux kernel
##  version from top-level makefile in set of kernel sources.  Patterns
##  to `grep` chosen based on kernel version identifiers in first
##  three lines of typical kernel top-level makefile.  Example:
##
##  $ head -n 6 Makefile
##  VERSION = 4
##  PATCHLEVEL = 9
##  SUBLEVEL = 66
##  EXTRAVERSION =
##  NAME = Roaring Lionus
##
##
## - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


script_name="showkversion"


if [ ]; then
    head -n 5 Makefile | grep ^VERSION | cut -d " " -f 3
    head -n 5 Makefile | grep ^PATCH | cut -d " " -f 3
    head -n 5 Makefile | grep ^SUBLEVEL | cut -d " " -f 3
fi

MAJOR=$(head -n 5 Makefile | grep ^VERSION | cut -d " " -f 3)
MINOR1=$(head -n 5 Makefile | grep ^PATCH | cut -d " " -f 3)
MINOR2=$(head -n 5 Makefile | grep ^SUBLEVEL | cut -d " " -f 3)

KERNEL_REVISION="${MAJOR}.${MINOR1}.${MINOR2}"

echo
echo "Kernel version in present kernel sources tree, per makefile, is ${KERNEL_REVISION}"
echo


exit 0



↑ ↓ Other useful shell tutorial references



↑ ↓ Other Computer Programming Languages

↑ ↓ Python Scripting Language



↑ ↓ Expect Utility by Don Libes

Good short examples covering range of tasks here at Robert Elder blog page, noting md5sum expect script example . . .

How to capture specific results during an expect script's execution:


- 2018-01-30 - Tuesday, picking up from last week researching how to redirect expect output and its spawned processes' output with filtering to log file. The first reference here at Stackoverflow repeats the useful lindex syntax. There is also mention of the expect manual and a syntax $::env(action) which can be expressed in an expect script to access an environment variable that is part of the controlling shell . . .

How to use expect's log_file key word in an expect script:

From the manual page for expect ___:

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