Bash shell scripting

Question

Recently I started working with shell scripting in Linux (newbie). I wanted to know the commands or the procedure to change from one folder to another within the loop? I mean how can I call different folders inside the executing loop? Presently, I'm renaming all the folders with no's say 1,2,3..... and using these inside the loop. I know this is not a good way to use scripting.

set k=1
while ( $k <= 17)

## initial path set
    cd /home/naren/Documents/BASELINE_INSP/FreeSurfer/$k/RSFC

Each time 'k' updates, move to different folders since I named all folders as no's.

OscarAkaElvis · Accepted Answer · 2017-09-26 12:04:17Z

2

Try this:

#!/bin/bash
for ((i=1; i <= 17; i++)); do
    #Changing folder inside the loop
    cd "/home/naren/Documents/BASELINE_INSP/FreeSurfer/${i}/RSFC"
    #Here you can execute something more if you want
done

answered Sep 26, 2017 at 12:04

OscarAkaElvis

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Comments

doktoroblivion · Accepted Answer · 2017-09-26 12:03:52Z

1

#
# Start with ID equal to zero and increment
#
ID=0

#
# then use a say a while loop
#
while [ ${ID} -lt 5 ]; do 
    echo "my dir is /here/${ID}/there"; 
    ((ID++)); 
done

answered Sep 26, 2017 at 12:03

doktoroblivion

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2 Comments

BDL Over a year ago

Although this code might solve the problem, a good answer requires an explanation of how/why this code helps.

chepner Over a year ago

I wouldn't write hybrid bash/POSIX code like this. The while loop is the correct method in POSIX, but then you must use something like ID=$((ID + 1)) to increment the variable. If you can use ((...)), then you could also more easily use a C-style for loop.

Armali · Accepted Answer · 2017-09-27 10:53:06Z

1

I mean how can I call different folders inside the executing loop?

Preferably, if you want to loop for all folders matching a certain pattern (which needn't contain numbers), just specify the pattern in a for loop:

for folder in /home/naren/Documents/BASELINE_INSP/FreeSurfer/*/RSFC
do  cd "$folder"
    # do something there
done

edited Sep 27, 2017 at 10:53

answered Sep 26, 2017 at 12:30

Armali

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Comments

kirecligol · Accepted Answer · 2018-01-19 10:30:24Z

-1

In order to write your code without numeration, you can use ls command which lists the files in the current directory or use ls [folder_name] to list the files in a folder, In order to assign the result to file use $ operator
Edit:
since ls has some pitfalls as @randomir mentioned it is better to use iteration as following:

for f in ./* do
  //do something with $f
done

edited Jan 19, 2018 at 10:30

answered Sep 26, 2017 at 12:06

kirecligol

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2 Comments

randomir Over a year ago

You should never do that.

kirecligol Over a year ago

Yeah you are right it seems the right way is something like that for file in somepath/*; do [ -e "$file" ] || continue some command "$file" done according to link

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