[SOLVED] Why are there two instances of this script

easysid · 2014-12-03 17:20:19

Maybe this question belongs in the bspwm thread, but to me this seems the right place to ask it.

Why does the panel script (bspwm_panel.sh) show two instances?

Here is the pstree branch

        ├─bspwm_panel.sh─┬─bar
        │                ├─bspc
        │                ├─bspwm_panel.sh   <-- this one
        │                ├─bspwm_panel_bar
        │                ├─conky───3*[{conky}]
        │                └─xtitle

The bspwm_panel.sh is the script to launch the panel, and bspwm_panel_bar.sh is the parser script for bar aint recursive.

here is bspwm_panel.sh. It gets launched from bspwmrc

#! /bin/sh

source $(dirname $0)/panel_config

if [ $(pgrep -cx bspwm_panel.sh) -gt 1 ] ; then
    printf "%s\n" "The panel is already running." >&2
    exit 1
fi

trap 'trap - TERM; kill 0' INT TERM QUIT EXIT

[ -e "$PANEL_FIFO" ] && rm "$PANEL_FIFO"
mkfifo "$PANEL_FIFO"

bspc control --subscribe > "$PANEL_FIFO" &
xtitle -sf 'T%s' > "$PANEL_FIFO" &
conky -c ~/Conky/bspwm_dec_conkyrc > "$PANEL_FIFO" &

bspwm_panel_bar.sh < "$PANEL_FIFO" \
     | bar -p \
           -g "$geometry" \
           -f "$FONT1","$FONT2" \
           -B "$BAR_BG" \
           -F "$BAR_FG" \
           | while read line; do eval "$line"; done &

wait

There shouls be one instance each of bspwm_panel.sh, and the bspwm_panel_bar.sh. What I do not get is where the second instance of panel script is coming from.

pgrep output

1617 /bin/sh /home/easysid/.scripts/bspwm_panel.sh
1624 /bin/sh /home/easysid/.scripts/bspwm_panel_bar.sh
1626 /bin/sh /home/easysid/.scripts/bspwm_panel.sh

Maybe its some aspect of wait that I am not familiar with.

Last edited by easysid (2014-12-03 18:34:14)

progandy · 2014-12-03 17:53:14

You run a new subshell for the while-loop. This manifests as a forked thread in the pstree output. If you don't need that, remove the "&" and the "wait".

Last edited by progandy (2014-12-03 17:54:09)

easysid · 2014-12-03 18:32:53

Ah, ok

 while read line; do eval "$line"; done

This pipe creates the second process. I guess it derives its name from the parent process.
Removing "&" and "wait" doesn't work, because the while-loop still shows up as a process. Removing the while-loop works and I get only two instances.
I need the while loop though, for clickable areas on bar. Thanks for resolving it.

I'll mark it as solved.

Arch Linux

#1 2014-12-03 17:20:19

[SOLVED] Why are there two instances of this script

#2 2014-12-03 17:53:14

Re: [SOLVED] Why are there two instances of this script

#3 2014-12-03 18:32:53

Re: [SOLVED] Why are there two instances of this script

Board footer