LQ Poll: What's your favorite Linux terminal trick?

Tonus · 10-19-2020, 06:06 PM

Quote:

Originally Posted by linpi

find . -name "*.php" | xargs grep 'search-string'

or find path -name "*.extension" | xargs grep 'search-string'

Great ! A little improved

Code:

find path -name '*.extension' -print0 2>/dev/null | xargs -0 grep 'searched string'

The "-print0" and -0 options to deal with spaces in filenames, the redirect to get rid of access errors for some files.

Indeed find and xargs, redirections and pipes are very useful !

joscer · 10-19-2020, 06:19 PM

using OMZ

JDoes · 10-19-2020, 11:32 PM

ss -tuna

It just sounds funny! And it is quite informative.

fraxflax · 10-20-2020, 02:57 AM

removed contents of this post as it was posted in error, how to remove it?

fraxflax · 10-20-2020, 03:37 AM

Quote:

Originally Posted by clamstrip

I like this!

Quote:

Originally Posted by bigearsbilly

Code:

alias path='(IFS=:;ls -1d $PATH |  nl)'

% path
ls: cannot access '/home/billy/R/usr/bin': No such file or directory
ls: cannot access '/home/billy/R/bin': No such file or directory
     1  /bin
     2  /home/billy/bin
     3  /home/billy/go
     4  /home/billy/usr/bin
     5  /sbin
     6  /usr/bin
     7  /usr/games
     8  /usr/local/bin
     9  /usr/local/games
    10  /usr/sbin

so here's the variant

alias path 'ls -1d `echo $PATH | tr ':' "\n"` | nl'

I also like it :-) and good not to be dependent of shell-specific env vars ... but clamstrip's variation above will not handle that you may have white-spaces in the directory names in the path....
also it makes more sense to me to force 'ls' not to sort the output, then you actually get the real search order of the existing paths, which nor bigearsbilly's bash specific alias handles (it will if you just add '-f' to 'ls' though).

So my variation of the alias covering for those instances follows:

Code:

 
 alias path='eval ls -1df `echo \"$PATH\" | sed -e"s/:/\" \"/g"` | nl'

Setting up an example using a stupid (but valid) search path with non-existing and existing dirs also with spaces in the names :-)

Code:

% echo $PATH
/tmp/first_in_path:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games:/usr/local/sbin:/usr/sbin:/sbin:/tmp/with white spaces:/non/existing/path:/non/existing/with white spaces:/tmp/last_in_path

% path
ls: cannot access '/non/existing/path': No such file or directory
ls: cannot access '/non/existing/with white spaces': No such file or directory
     1	/tmp/first_in_path
     2	/usr/local/bin
     3	/usr/bin
     4	/bin
     5	/usr/local/games
     6	/usr/games
     7	/usr/local/sbin
     8	/usr/sbin
     9	/sbin
    10	/tmp/with white spaces
    11	/tmp/last_in_path

fraxflax · 10-20-2020, 04:32 AM

Quote:

Originally Posted by Tonus

Great ! A little improved

Code:

find path -name '*.extension' -print0 2>/dev/null | xargs -0 grep 'searched string'

The "-print0" and -0 options to deal with spaces in filenames, the redirect to get rid of access errors for some files.

Indeed find and xargs, redirections and pipes are very useful !

Yupp, you can also utilize the find '-type' arg to only get files not having to redirect to /dev/null and '-exec' arg to handle white spaces doing the grep not having to pipe it to xargs:

Code:

 
find path -type f -name '*.extension' -exec grep 'searched string' {} \;

I find using 'find' very useful with

Code:

 
-type f -exec grep -il 'searched string' {} \;

to locate files containing certain data ... I use it all the time :-)

If you want to have both the filenames and the matched line containing the 'searched string' in the same output, the way to go would be 'find -print0' in combination with 'xargs -0' as suggested (that way grep gets several filenames as argument and will print which file it matched the string) and if you want to get rid on errors of files that cannot be read, the redirect of stderr is also required ... but '-type f' is still useful as there is no need to feed grep with directories :-)

heinjh · 10-20-2020, 07:52 AM

Because I am lazy... I added a bunch to my .bashrc

Code:

# Use "gh" to search through history for a term
# Type in the search term after the gh like   "gh bash"
# This will search through the history for anything with "bash" in italias gh='history|grep'
# list only hidden directories and filesalias l.="ls -d .* --color=auto'
# pipe out directory listing for viewing with the long formatalias lsl='ls -lhFA|less'
# use "c" to clear the screenalias c='clear'
# use "h" to bring up historyalias h='history'
#use ".."  to quickly move to parent directory.alias ..='cd ..' 
# combined two commands that opens .bashrc to edit, and reloads it after the editor exits to implement changes.alias editbashrc='vim ~/.bashrc ; source ~/.bashrc'
# function to make directory and then change into itmkcd ()
 {
  mkdir -p -- "$1" && cd -P -- "$1"
 }

porphyry5 · 10-20-2020, 11:07 AM

Quote:

Originally Posted by mark.schutte

What's my favorite Linux trick? Not really a trick, but it is my favorite command line short-cut of all time... it's the "!$". Nothing saves more typing that !$. I can't live without it. If you've never heard of it, typing !$ on the command line repeats the last white-space separated <ANYTHING> from your previous command line. I love using !$ whenever the last thing I typed was so super long path or long filename. Why type it again? Simply hit !$. :-)

Thanks for this tip, but you don't have to type existing long paths or filenames if you use mc (midnight commander) file manager. It has commands "Ctrl-x p" and "Ctrl-x t" to put them on the command line for you.

And if you use the text editor vim, these lines in your .bashrc let you edit command lines as if you were in vim, instead of having to learn corresponding bash line edit commands (similar for emacs users too, I think).

Code:

set -o vi
shopt -s dotglob extglob

resolv_25 · 10-20-2020, 12:10 PM

Good thread this one :-)

Simple checking if previous command is successful, it can be within the script or chained command (command1; echo $?):
$?

Example:

Code:

mysql $db < db_backup_tmp.sql
if [ $? -eq 0 ] 
then
    echo "Db import successfull."
else
    echo "Mysql import not successfull."
    echo "Exit..."
    exit;			
fi

dr_agon · 10-20-2020, 01:07 PM

I like the colored command prompt with information about current git branch. The colors differ for clean repo, unstaged changes and staged changes. I have this in my .bashrc :

Code:

#---
# git color prompt
# Configure colors, if available.
if [ -x /usr/bin/tput ] && tput setaf 1 >&/dev/null; then
    c_reset='\[\e[0m\]'
    c_user='\[\e[0;32m\]'
    c_path='\[\e[1;36m\]'
    c_git_clean='\[\e[0;37m\]'
    c_git_staged='\[\e[0;32m\]'
    c_git_unstaged='\[\e[0;31m\]'
else
    c_reset=
    c_user=
    c_path=
    c_git_clean=
    c_git_staged=
    c_git_unstaged=
fi

 
# Function to assemble the Git parsingart of our prompt.
git_prompt ()
{
    GIT_DIR=`git rev-parse --git-dir 2>/dev/null`
    if [ -z "$GIT_DIR" ]; then
        return 0
    fi
    GIT_HEAD=`cat $GIT_DIR/HEAD`
    GIT_BRANCH=${GIT_HEAD##*/}
    if [ ${#GIT_BRANCH} -eq 40 ]; then
        GIT_BRANCH="(no branch)"
    fi
    STATUS=`git status --porcelain`
    if [ -z "$STATUS" ]; then
        git_color="${c_git_clean}"
    else
        echo -e "$STATUS" | grep -E -q '^.[A-Z\?]'
        if [ $? -eq 0 ]; then
            git_color="${c_git_unstaged}"
        else
            git_color="${c_git_staged}"
        fi
    fi
    echo "$git_color[$GIT_BRANCH]$c_reset"
}
 
PROMPT_COMMAND="PS1=\"${c_user}\u${c_reset}:${c_path}\w${c_reset}\$(git_prompt)\$ \" ;"

#---

For machines I connect to remotely I put colored hostname in the prompt, and for root I have user in red:

Code:

PS1='${debian_chroot:+($debian_chroot)}\[\033[0;31m\]\u\[\e[0;32m\]@\h\[\033[00m\]:\[\033[01;36m\]\w\[\033[00m\]\$'

(all colors for black background!)

djk44883 · 10-20-2020, 06:27 PM

Quote:

Originally Posted by Septuagerian

watch -n 2 sensors.

Although I suppose there are more, sensors is the only practical application I've ever found for watch as well!

Quote:

Originally Posted by Ourck19

poweroff !!!
Best & nice day
Fred.

agreed, Like the quick and easy

ondoho · 10-21-2020, 03:49 AM

Quote:

Originally Posted by resolv_25

Simple checking if previous command is successful, it can be within the script or chained command (command1; echo $?):
$?

that's actually part of my prompt:

Code:

PS1="...\${?#0}..."

i.e., only show the status if it's not 0.

josephj · 10-21-2020, 04:07 AM

Quote:

Originally Posted by resolv_25

Good thread this one :-)

Simple checking if previous command is successful, it can be within the script or chained command (command1; echo $?):
$?

Example:

Code:

mysql $db < db_backup_tmp.sql
if [ $? -eq 0 ] 
then
    echo "Db import successfull."
else
    echo "Mysql import not successfull."
    echo "Exit..."
    exit;			
fi

If you're using a recent version of bash, this is a cool alternative:

Code:

mysql $db < db_backup_tmp.sql
rc=$?
if (( rc )) 
then
    echo "Mysql import failed with code [$rc]"
    exit "$rc"			
fi

echo "Db import successful"

grail · 10-26-2020, 10:13 PM

So I see a lot of my faves already listed, but one I hadn't seen which I do on most servers these days is add a little colour to man:

Code:

# Less Colors for Man Pages
export LESS_TERMCAP_mb=$'\E[1;33m'        # begin blinking
export LESS_TERMCAP_md=$'\E[1;33m'        # begin bold
export LESS_TERMCAP_me=$'\E[0m'           # end mode
export LESS_TERMCAP_so=$'\E[1;32;5;246m'  # begin standout-mode - info box
export LESS_TERMCAP_se=$'\E[0m'           # end standout-mode
export LESS_TERMCAP_us=$'\E[04;1;36m'     # begin underline
export LESS_TERMCAP_ue=$'\E[0m'           # end underline

A few of my standard aliases:

Code:

# useful aliases
alias ls='ls --group-directories-first --color=auto -F'
alias ll='ls -l'
alias la='ls -A'
alias lh='ll -h'
alias grep='grep --color=tty -d skip'
alias less='less -XRFmx2'

Lastly, so my terminal is the same as my preferred indenting style, add the following to .bashrc:

Code:

tabs -2

DarrenDrapkin · 10-30-2020, 09:53 AM

I know you will call me a boreing old so and so, but here's a second vote for tab completion. Like most trickery it does not always work, and like most trickery, can get you out of trouble very quickly, when it does work.
At one stage I had bash so well trained that I could do some very sophisticated coding, without even touching an editor to write scripts in.