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Accepted
yukashima huksay
Asked: 2018-01-05 10:42:19 +0800 CST

How to use read -ra inline?

  • 772

I need to run a command from python so I'm doing:

os.system('IFS=".";for f in data/* ; do read -ra ADDR <<< "$f";     mv "$f" "data/${ADDR[-1]}"; done;')

but it says :

sh: 1: Syntax error: redirection unexpected

But if I run this in bash it works fine:

IFS="."
for f in data/* 
do 
    read -ra ADDR <<< "$f"
    mv "$f" "data/${ADDR[-1]}"
done;

It works just fine. How can I fix it to work in one line?

bash

2 Answers

  1. Best Answer

    @steeldriver has pinpointed the problem. You could solve it with:

    import subprocess
subprocess.run(['bash', '-c', '''
    IFS="."
    for f in data/*; do
        read -ra ADDR <<< "$f"
        [[ ${#ADDR[@]} -gt 0 ]] && mv "$f" "data/${ADDR[-1]}"
    done
'''])

    but at this point, you're probably better just doing the whole thing in python instead of calling out to bash: something like

    for f in os.scandir("data"):
    if f.is_file():
        addr = f.name.split(".")[-1]
        if f.name != addr:
            os.rename(f.path, "data/"+addr)
    • 5

  2. Following @steeldriver comment and @glenn jackman answers:

    os.system('/bin/bash -c \'IFS=".";for f in data/* ; do read -ra ADDR <<< "$f";     mv "$f" "data/${ADDR[-1]}"; done; \' ')
    • 1